Pick n pay and Rcs

I have an RCS account through pick n pay. Every time I make a payment its a hussle!! Last month I made a stop order from my account to their standard bank account, sent them a bank statement, reference and amount paid so they can credit my account. To this day not a single call from them....all I get is back and forth emails asking the same question over and over...my email has my contact number but no one is bothered to call me. All they keep saying is that they didn't receive my payment!!!!!!! This feels like a trick to get me in arrears or to make me pay double. I have now paid my instalment for this month and have to deal with more drama from them. They have no idea what customer service is!!!!! I'm seriously annoyed. Can someone please call me urgently!