My girlfriend left her job (after a contractual notice period) at the beginning of July. At the end of the month, she received her final paycheque, which should have consisted of the several days worked at the beginning of July, and her remaining holidays owed. Instead, she received equivalent to a whole months pay (about 1.7k).
She believes it is likely due to her manager forgetting to process her leaving paperwork in time. The company emailed her to acknowledge the mistake, and has asked that she pay the amount back in full, but did not mention the amount she should have been paid instead.
We will both be leaving the country (UK) next week to move abroad and start new jobs, so I told her not to worry about paying it back. Any thoughts?