Aaargh, what does 'CUI' mean?

[madamez]

Paid a cheque into my account, was checking my balance at the hole in the wall and the slip shows the sum with a - sign and CUI beside it. WTF has happened?

I think it means currently under investigation. I would be inclined to phone your bank.
Hope this helps

Thanks Jenny It's my housing benefit cheque, and of course this would happen just before a bank holiday.