We have come across others on the Apple forum who are getting this error message – here is a UK forum link to help you:
https://discussions.apple.com/thread/3413395?start=15&tstart=0
If you are unsure of what to do then you need to contact Apple support line direct which in the UK is: 0800 048 0408
Apple support for clients in South Africa:
https://www.apple.com/za/support/
Apple support for clients in Spain:
https://www.apple.com/es/support/
Apple support for clients in Italy:
https://www.apple.com/it/support/
Apple support for clients in Poland:
https://www.apple.com/pl/support/
Apple support for clients in Turkey:
https://www.apple.com/tr/support/