Rage does not respond swiftly to customer’s enquiries

I have paid off my account and asked the store lady to assist with closing off the account and she told me she cant do it from her side and that i must send an email to cancel my account , which i did but until to-date they have not yet responded. I went back to the store in Vanderbijlpark Checkers Hyper Shopping centre and the same lady told me that they will respond and that they will assist but nothing as yet. Unfortunately this account reflects bad on my credit as it accumulates interests even though i paid it off.