<prompt> Human: Three weeks ago I initiated an ACH transfer at bank A to move money from bank B to bank A. This is a process I have done at least a hundred times in the past decade with these two accounts and these exact settings from the linked accounts.Money was deposited in bank A almost immediately. Two weeks later, funds were never debited from bank B.I called bank A, they confirmed that the funds had been deposited and there was no hold or any other error on their end.I called bank B and told them that money was pulled from their side but I have no idea where from. They treated me like an idiot and told me to contact bank A, for surely, they cant see any transaction attempt for the amount I withdrew.I asked bank B to please initiate an investigation for that transaction amount because I dont want to be on the hook for this amount years down the road when they finally pull their head out of their A and find where the money was actually pulled from.Now its 3 weeks later and, again, I was told to talk to bank A, because bank B has nothing to do with this transaction.Now Im at a loss because neither side will help me track down where almost 750 came from - but it is fully there in bank As transaction list and nowhere to be seen in bank Bs. What are my options? I want to have management at bank B sign a document stating that Im off the hook for the transaction from three weeks ago or else initiate an investigation into where the funds were pulled from because this is getting ridiculous. They can surely search transactions in the very specific and odd amount I made within the date range it would have cleared, can they not?EDIT, 1 hr later: So, the first person I talked to a week ago at the debited bank B made it sound like she had never heard of the ability to transfer funds between accounts online. I knew I wasnt getting far with her but she said she would look into finding out for me and calling me back. She never did.I called Bank B again just today and verified the routing and account information. What I found out was actually kind of stupid: Their routing number changed. I have been using an old routing number for close to a decade and when I told him what it I was using, he recited back a completely different number. The bank never changed hands, they just decided to change routing numbers and not update anyone.So now, I called bank A where I initiated the transfer and told them hey, the routing number for the other bank apparently stopped working 3 weeks ago, so the money is being pulled from parts unknown, whats going to happen since its already been credited to my account? I was told that the transaction will eventually be denied but when, who knows? and the funds removed from my account at bank A.This kind of behavior seems VERY prone to fraudulent activity - the accounts were merely verified by a few small transactions years ago. If the routing numbers get reused, you could be tied into someone elses account with the ability to withdraw funds that arent yours. I really hope it isnt being reused, because Id hate to be the reason some little old lady cant buy groceries this week just because some bank didnt think it prudent to let their customers know their routing numbers had changed after being used without incident for a decade.tl;dr: Bank changed routing numbers, didnt let me know. I pulled money from who knows where.  <response>: Honestly, Im all for being above-board on everything. But if you tell someone money came out of nowhere, and they tell you to go away, and you tell them again, and then you ask them to verify and confirm and they confirm...At one point I would just go OK, I tried. Keep that 750 available in your account for 2 years just to make sure you pass at least one year-end closing of the books, and then if nothing happens within those two years, just keep the money. Keep documentation that you tried to tell them, so if they come after you later, you can tell them to go suck a lemon. 