Administration inefficiency

I opened a loan account with RCS in Builders Warehouse. The 1st payment was done through EFT on 30 Nov 2020. The email for sending proof of payment (this comes from their statement) was ***. I further discovered my address including my email was wrongly written. I phoned RCS and explained. They promised to correct it and told me to send (email) ***. I went back to my account beneficiaries and changed the email. in spite of that, I kept on receiving emails that said I did not pay. I phoned them (which I find it not so friendly, as you hold the line till airtime got finished!). They promised to correct this. I told them that I will again make a payment on 30 Dec 2020 through EFT, which I did. Even today I am receiving sms that says my account has not been paid, is in arrears. Could they please correct my account as I will be getting bad credit. My name is V H Rashe.