Closing account

I have been trying to close my account with RSC since the beginning of May 2015. The account was settled in full on the 1st of May. I faxed the letter requesting closure of the account a week after I paid the account in full. The letter was accompanied by a copy of my ID. No one at RSC acknowledged receipt of the fax.<br> <br> On the 15th of May I got the monthly statement telling me I 'owe' R24,76 'interest' on the account. I emailed them and pointed it out that it is impossible to owe interest on R0.00. Again, I sent them a copy of my ID and asked them to close the account. No one acknowledge my email.<br> <br> Today, 17 June, I again got another statement telling me that I owe the R24,76.<br> <br> How difficult is it to close the account?