Horrible customer service

RCS is failing to allocate my payment to my credit card account. I have a credit card with RCS and repayment is via debit order but for some reason In October the debit order did not run and I called to enquire and I was then informed of a technical issue. I was then told to pay via eft which I did but unfortunately I paid into RCS store card suspense account. I then called and explained and I was told to send a proof of payment. I send it and this was over 3 weeks ago. I was told the payment will be allocated in 5 days even today the payment is not allocated I was charged late payment fee and interest unfairly and now I get calls from collections please help me.

Marumo Mokoena ***