Unacceptable Billing

I have an account with makro on which they don't record my payments on their statements. I've been paying my installments every month before the 7th as advised. I recently made an arrangement to pay them R400.00, of which I kept my promise and paid but they kept on adding interests. I contacted them via phone and spoke to their manager by the name Pillay, who promised to investigate till this day. Further on they sent me an sms on the 4th of September stating that I agreed to pay R500.00, telephonically a day before. Of which I did not receive any calls from them. I asked them to pull a tape to verify this allegation of which they failed to do. From there on they handed me over to MBD. I then phoned them on the 28th of Septembers and spoke to Tenikwe who was really unfriendly. Again when I phoned them they couldn't help, from Danzel to TSHEPO - all couldn't help. They asked me to send an email to [Email Removed] and to [Email Removed] Till this day neither one of the two responded. I cannot continue paying whilst they don't keep records and keep on adding interest, it is unprofessional and shows lack of incompetence!