If it was a cheque they'd presumably be able to identify it through their paying-in records? They could then contact the customer and have a new one made out so she wouldn't have to pay it back.I assumed it to be a cheque in a envelope or something similar.
It must have been cash, maybe in envelopes from an atm. She's obviously a daft bint, but you'd have thought they'd have systems to prevent things like that occurring.

Some of you are as bad as ****ing her 