Paying for things I don't know of

Had a account with MR price lost my job and could not pay the R400 interest increased overtime and I had to pay more ... My account was handed over to nimble group, they gave me a discount offer and I paid that off a few year ago and requested for the account to be closed. They reached out again claiming I still owe the a amount off R395 after I already paid I ignored it then last month I got a email from SSD Shapiro Shaik Defries & Associates stating I still owe a amount of R634 I made a payment of R635 on the 25th march 2026 few days after that I got a call the lady said I still owe R298,75 because I paid R635 and I was supposed to pasy R638 so basically because I left out the 3rand I now owed R298,75 and it's keeping my credit score on a negative so I do not recommend anyone to open a account with Mr Price this is crazy