Failed when installing SQL 2014 CU5

I'm trying to install SQL 2014 SP1 CU5 on a 64bit instance but am having an issue.

I've managed to apply this to 2 of the 3 instances on the server, but the third simply wont install.

After trying to install the patch, i get the error : 

Failed to shutdown the instance with process ID XXXX. Error encountered: Microsoft.SqlServer.Configuration.Sco.ScoException: The requested control is not valid for this service.   ---> System.ComponentModel.Win32Exception: The requested control is not valid for this service.

The log file reports the following (massive dump).

Overall summary:
  Final result:                  The patch installer has failed to update the following instance: STG. To determine the reason for failure, review the log files.
  Exit code (Decimal):           -2061893608
  Start time:                    2016-03-18 11:54:44
  End time:                      2016-03-18 12:13:08
  Requested action:              Patch

Instance STG overall summary:
  Final result:                  The patch installer has failed to update the shared features. To determine the reason for failure, review the log files.
  Exit code (Decimal):           -2061893608
  Start time:                    2016-03-18 11:56:52
  End time:                      2016-03-18 12:13:05
  Requested action:              Patch

Machine Properties:
  Machine name:                  SQL01
  Machine processor count:       40
  OS version:                    Windows Server 2012
  OS service pack:
  OS region:                     United Kingdom
  OS language:                   English (United States)
  OS architecture:               x64
  Process architecture:          64 Bit
  OS clustered:                  No

Product features discovered:
  Product              Instance             Instance ID                    Feature                                  Language             Edition              Version         Clustered  Configured
  SQL Server 2014      DWH                  MSSQL12.DWH                    Database Engine Services                 1033                 Enterprise Edition   12.1.4439.1     No         Yes
  SQL Server 2014      DWH                  MSSQL12.DWH                    Data Quality Services                    1033                 Enterprise Edition   12.1.4439.1     No         Yes
  SQL Server 2014      DWH                  MSAS12.DWH                     Analysis Services                        1033                 Enterprise Edition   12.1.4439.1     No         Yes
  SQL Server 2014      SRS                  MSSQL12.SRS                    Database Engine Services                 1033                 Enterprise Edition   12.1.4439.1     No         Yes
  SQL Server 2014      SRS                  MSRS12.SRS                     Reporting Services - Native              1033                 Enterprise Edition   12.1.4439.1     No         Yes
  SQL Server 2014      STG                  MSSQL12.STG                    Database Engine Services                 1033                 Enterprise Edition   12.1.4100.1     No         Yes
  SQL Server 2014      STG                  MSSQL12.STG                    SQL Server Replication                   1033                 Enterprise Edition   12.1.4100.1     No         Yes
  SQL Server 2014      STG                  MSSQL12.STG                    Data Quality Services                    1033                 Enterprise Edition   12.1.4100.1     No         Yes
  SQL Server 2014                                                          Management Tools - Basic                 1033                 Enterprise Edition   12.1.4439.1     No         Yes
  SQL Server 2014                                                          Management Tools - Complete              1033                 Enterprise Edition   12.1.4439.1     No         Yes
  SQL Server 2014                                                          Client Tools Connectivity                1033                 Enterprise Edition   12.1.4439.1     No         Yes
  SQL Server 2014                                                          Client Tools Backwards Compatibility     1033                 Enterprise Edition   12.1.4439.1     No         Yes
  SQL Server 2014                                                          Client Tools SDK                         1033                 Enterprise Edition   12.1.4439.1     No         Yes
  SQL Server 2014                                                          Data Quality Client                      1033                 Enterprise Edition   12.1.4439.1     No         Yes
  SQL Server 2014                                                          Integration Services                     1033                 Enterprise Edition   12.1.4439.1     No         Yes
  SQL Server 2014                                                          Master Data Services                     1033                 Enterprise Edition   12.1.4439.1     No         Yes

Package properties:
  Description:                   Microsoft SQL Server 2014
  ProductName:                   SQL Server 2014
  Type:                          RTM
  Version:                       12
  SPLevel:                       1
  KBArticle:                     KB3130926
  KBArticleHyperlink:            http://support.microsoft.com/?kbid=3130926
  PatchType:                     QFE
  AssociatedHotfixBuild:         0
  Platform:                      x64
  PatchLevel:                    12.1.4439.1
  ProductVersion:                12.1.4100.1
  GDRReservedRange:              12.0.2200.0:12.0.2290.0;12.0.4200.0:12.0.4299.0
  Installation location:         c:\dd1742c02441ba2ffc72e8397443\x64\setup\

Updated product edition:
  Instance             Edition
  STG                  Enterprise

User Input Settings:
  ACTION:                        Patch
  ALLINSTANCES:                  false
  CLUSTERPASSIVE:                false
  CONFIGURATIONFILE:
  ENU:                           false
  ERRORREPORTING:                false
  HELP:                          false
  IACCEPTSQLSERVERLICENSETERMS:  true
  INDICATEPROGRESS:              false
  INSTANCEID:                    <empty>
  INSTANCENAME:                  <empty>
  QUIET:                         false
  QUIETSIMPLE:                   false
  SQMREPORTING:                  false
  UIMODE:                        Normal
  X86:                           false

Rules with failures:

Global rules:

There are no scenario-specific rules.

Rules report file:               C:\Program Files\Microsoft SQL Server\120\Setup Bootstrap\Log\20160318_115443\SystemConfigurationCheck_Report.htm

Regards,

Andy