<prompt> Human: Since last December Ive been getting irregular deposits into my checking account in different amounts totaling more than 4,000. The payments description is FIS_Prepaid Card Funds Trf. Ive contacted my bank a number of times, but they say they have no information beyond the transaction description. I looked up FISs number and contacted them, but they said they have no information and cant look up the deposits.I have only one credit card and one debit card through my bank, and Ive those that exclusively for the last 8 years. Before that I had an account with Wells Fargo. Ive never had a prepaid debit card that I can remember, and certainly not one with 4,000 left on it. There have been no disputes of any charges on a debit or credit card in the last year, and I would remember anything outstanding for this much money.I am being careful not to spend the money, since there is a good chance this is a mistake. Having to keep track of how much of my account balance is untouchable is annoying. How can I find out where this money is coming from and why?The deposits dont seem to follow a pattern:Dec 19 - 1101.85Dec 27 - 767.60Jan 25 - 493.25Mar 22 - 1739.86Edit: Thank you for all the advice, knowing what to ask and where to ask it should help! Im going to pressure my bank tomorrow and ask for the full ACH deposit instructions and see if that leads somewhere useful. Ill try the FIS EFT Investigations division next. If that fails Ill ask my bank to open a fraud investigation and send them a certified letter.Final Edit: The FIS phone number led nowhere. If you want to run around a hilariously automated system with no exits, I recommend it. Thankfully, my bank was more helpful. Once I started asked for ACH transaction details and the ID of the sender and stated they must have it, I was transferred to someone able to look up that information. They gave me a new company name not FIS and a trace number. Thank you uUGetDatThingiSentYa for the correct terminology! The new company was able to tell me the source of the payments and sort everything out. Thank you to everyone for the help, I had no idea this would be so popular! Assistant: Having to keep track of how much of my account balance is untouchable is annoying. open a savings account and toss the money into there so that its untouched should someone finally come looking for it, but its out of your line of sight so its no longer annoying you.and you get to keep whatever interest it generates :-Human: Good idea! Im a little worried about a reversal of the mistake in my checking account followed by auto-paying bills causing an overdraft if I move it.  <response>: Youll be fine on this front. Worst case scenario, you have to escalate to a manager or two. I guarantee you that your bank will refund the money once they go back and listen to prior calls. If they dont, contact the CFPB and I guarantee you they will now.Moving the funds to a savings account for a couple years is a completely safe bet as long as the account is with the bank with the checking account. They will see your obvious attempts to be honest. 