Payment issues with RCS

Not the first time having issues regarding payments with RCS. Installment due for April was R260.68 on the 2nd April i paid R300. They started to phone me and sending statement, i am overdue, i send the POP on the 18th April, I have used the wrong reference number, BUt POP was send.

They keep phoning me, and i told them POP was send, Then i asked them to please stop phoning me i have to pay for all those calls they make everyday, just make a note as POP was send, and they have send it to head office. Once again a lady phoned, so i explained everything to her, so she tells me that yes but i still owe money as i only paid r300 and not R539 as i am overdue, so i told her but i am not overdue as i have made mh payment for April, just the wrong reference was used. Since the 18th, they still phone me everyday, and i have to pay for all these calls, and no one has given me feedback as to if my accouct was updated and payment allocated. I have even blocked my Makro account due to this bad service i am receiving from RCS, i would not ever recommend RCS to anybody.