We have a customer who is asking for refunds on his business (LLC) account for unauthorized debit card transactions going back 11 months. During those 11 months he has come in the bank three times telling us his girlfriend has been using his card and he wants a new one. On all three occasions the employee has asked for a list of unauthorized charges, only to be told he would get back with us. In addition, on the last reissue he told the staff member that he was going to keep the new card in the same location and let her use it so he could catch her in the act.
I want to deny him for negligence and delay in reporting unauthorized use. Does anyone see an issue with this?

Not only would I deny for the reasons you state, I also would not issue another card.