Medi Clinic Gardens accounts department failed to capture my payment and now I have a bad credit rating.

I went to ER at Mediclinic Gardens in September 2020 from passing out. I made a payment with a card machine of R720.40.

For the past year I have had their debt collectors ER CONSULTING harassing me to make payment even though I have already made payment. I have sent my statement showing my proof of payment as well as the email from my FNB app proving I've made the payment. They keep asking me for a payment profile however there is no payment profile for card payments. FNB have mentioned to me many times that what's on the statement is my proof. They have now given me a bad credit rating for refusing to pay twice. All of this because their accounts department failed at capturing my payment.