Cell C the worse Company Ever!!!!

Cell C is such a bad company. I paid my two contracts completely in June 2020, then in November 2020 I got an email from Cell C Lawyer’s NDS saying I didn’t pay my one account. I went into the store to query this and showed them proof of my payment just for them to see my money laying in their suspense account. They apologized and promised me they will clear my name. Now I want to buy a car. My loans are being rejected because of their error. I called their customer care and the lady was soo rude, telling me I need to sort it out and even dropped the call while I’m still talking to her. This is very bad service & I’m fuming with Cell C. Please can you help??