Bank admits screw up, screwing me, HELP?

Okay first off I'll say I'm completely aware I need to keep track of when I make payments, and having the bank manager go so far as to give me a binder when I came in to fix this as me a little on edge.

So here's what happened. Today I wake up and get a call from American General, saying that they never got a payment on one of my accounts. I call them and start geeking out because I know I've made this payment, I made payments to both my accounts while I was in there. So he asks me if I have my receipt, which I don't. I work in my car, I keep shit in there, when sunday rolls around, I clean house. I don't have a filing system. I know what I take care of and what I don't. I'm not stupid. Anyway, my cars in the shop, one of our dogs is lost, I'm broke, apparently forgot to pay two of my credit cards last month, which I swear I paid, and all this crap is starting to pile up on me. I'm at my breaking point, and I know I made that freaking payment.

So I get a call my cars done, and I go pick it up, and head to the bank to figure out what the hell happened to my money. My banks shows I took out the money. This bank doesn't have a pay online option, so I have to make payments there, cash check or money order. Sure once again I'm making my life difficult by paying cash, oh well. Still not my fault.

I get in there, and the manager, whom I've had a few long chats with when my x boyfriend dumped on our co-signed loan together, he trust me, even let me take the insurance off the car cause it's in pieces in my driveway. Drops a fantabulos bombshell on me.

They checked the amount that I paid against other accounts. Down to the second the transactions were made. Get this. They're pretty sure they've posted it to the wrong account. They all but admitted they screwed up. He tells me he's trying to contact the costumer, and make an "implication of consent" so he can get my money back and post it to my account. The transactions were made within 45 seconds of eachother, being that I made both payments on the same day, at the same time.

I suggested having HIM(other account holde) produce a receipt for the supposid payment if claims he made the payment, but they said it won't matter since it's already posted to the account.

So what it boils down to is if I don't have a receipt I get screwed, and I'm a month late on my payments. I have to wait to find out if this dude is honest or not, and if he's not, then I'm out a months payment and I'm a month late. This is total bullcrap, can someone pls help me?

CT