Product: Credit card

On XXXX XXXX, I called Fifth and Third Bank to pay my credit card bill of {$1400.00} due that day.. The person on other line told me he 'd have to check with supervisor since its for the total amount due and not the smaller amounts I normally paid. I explained I was paying it all off, etc., and he was still very hesitant and sketchy about it. 
I finally got the payment made after taking about an hour, much longer than normal. He gave me confirmation number and we went about our days. 
I received statement from Fifth & Third a few days later on like XX/XX/XXXX or so, showing the payment being made, and account balance being {$0.00} due on XX/XX/XXXX 
Therefore I assumed there was no issue with payment, and planned to not pay any attention to account anymore since it was paid off ... 
This week on XX/XX/XXXX, I received XXXX letters from 5th and 3rd, XXXX I opened first showing that my credit card with them is now cancelled due to delinquent payments, the other letter being a new statement showing a new balance of {$1400.00}!!! 
I looked closer at statement and it has Payment Reversal happening on XX/XX/XXXX! 
I checked my bank account and sure enough payment is no longer there. 
I 've called them and asked why it was reversed, they informed me it 's because the account number was n't taken right that day!!! 
I never received any letter, call, or email telling me that the payment was reversed, and was under the impression that the {$1400.00} was out of my bank account and that the bill was paid off due to the statement they mailed me showing it was paid!!! ( I was n't concerned with checking my bank account at the time, as I had {$25000.00} in it to pay off bills and purchase a tractor, was no reason for me to look for that charge, it should 've gone through.. ) When that employee didnt correctly complete my payment, they still sent out a XXXX balance statement, and when the error was caught, never informed me so technically, I did n't pay XX/XX/XXXX or XX/XX/XXXX 's bill because I had no clue I even had a balance with them!! 
I received XX/XX/XXXX the statement showing me all this so they left me in the dark, and have now screwed up my credit report! 
They 've reported this as XXXX month delinquent account now, even though it was their fault for not informing me of THEIR mistake!! 
I understand whats happened and realize I 'll be paying the {$1400.00} now asap ( I bought my tractor just last week so all that money is gone, and I thought this was already paid off so now put me in the hole!! ). 
However, I need them to rectify my credit report and take off these false claims of a delinquent account the past XXXX month!! 
I 've received XXXX letters from XXXX other credit cards I had this week, XXXX XXXX and XXXX XXXX, both of which are fully paid off, and they just lowered my credit line by a total off {$12000.00}!!! I just lost that much credit cause of 5th and 3rds stupid mistake with my payment and failure to notify me! 
They falsely informed me that the account was paid and good, and failed to inform me of their mistake all while XXXX up my credit I 've worked hard to build and need in the future!! 
I 've gotten no where on the phone to remedy this and need help to talk to someone who will actually help!! 
Please help, every day they ruin my credit even more!