My previous employer (UK civil service) paid me my full monthly salary the month I left. The month I left (August 2017) I did around 5 days of work due to how my fixed contract work (11 months starting 5/09/16) and annual leave. Realistically they should have paid me for just those days I worked but I assume there was a clerical mishap.
It didn't really click with me this was the case till months after and assumed there being no contact it didn't matter. Today I received a letter stating all this and that I have pay the excess back. Is this right? I mean conceptually it makes sense but why would I not have been notified earlier, personally I feel like it's been long enough and not even my fault. Not to mention I don't even have the money to pay them back at this point. This area I really have no idea and my work life is very short. Any advice would be greatly appreciated.