im sorry , but if its owed its owed...I knew someone on a temp contract with the NHS after they left she kept getting paid,she never touched it or spent it , got a knock on the door one day and mr plod was there and she was arrested.
She paid it straight back but still ended up in court and a police caution against her name.
I dont think think for one one minute this would happen to you but it really depends how far the employer would take it .
You must have been on good money if you were overpayed that much over a few months and didnt think there was a mistake !!! could do with a job like that myself