RCS account payments not declared

I am unhappy with how RCS handle account payments. I paid R1000 for the month of January 2025. I usually pay before month end. The first week of February, I received a call from them, stating that I have not paid my account. They requested proof of payment, and I emailed to them. But, they did not get back to me. I paid for February 2025. They called today, saying they did not receive my payment for February. This issue is overwhelming, knowing that I am a loyal customer, who pays on time and above what they requested. Please assist with this matter.