a similar thing has just happenned to me since I started a new Job a few months ago - they have been paying me a full-time wage; even though I only work part-time & signed the contract for part-time hrs. I reported this error to my manager as soon as I realised ie after the 2nd month/wage (as I started mid month - I did not notice the overpayment in the first month/wage). However 3 months later I am still being over paid (though I have been informing my manager, HR & payroll each month!) I think someone in HR have finally taken responsibility; and I am expecting a 'deduction agreement letter any day now. However, the 'over-payments' have gone staight into my overdraft - does that count? do I still have to pay it back??