Refusing to send me paid up letter

I bought my storage base and I asked for settlement to be on the 26th November and I paid it same day. And they are telling me I still owe because to them it only appeared on the 28th and I had to remove my salary on my bank and I am still Debited making my account to be on minus with almost daily bank charges and I am gatvol..I keep calling and I am sending back and forth and asked over and over to send proof of payment and proof of settlement letter with the date agreement of settlement ***