Hi,
OK, it downloaded after I did as you suggest and repaired the Apple update but then I had a message tosay iTunes had stopped working and this was the details of the problem:
Problem signature:
Problem Event Name: APPCRASH
Application Name: iTunes.exe
Application Version: 12.3.1.23
Application Timestamp: 5620c96d
Fault Module Name: CoreAudioToolbox.dll
Fault Module Version: 7.10.5.0
Fault Module Timestamp: 55e61a16
Exception Code: c000001d
Exception Offset: 00000000005f9630
OS Version: 6.1.7600.2.0.0.256.1
Locale ID: 1033
Additional Information 1: 86a5
Additional Information 2: 86a599f99c7c0b061be0ac10bc599c0b
Additional Information 3: fed6
Additional Information 4: fed622b47b1ad2e473bfcb250c527fd0
Any further ideas?