Accounts being in areas

I had a contact with Blue Label Connect since 2020, they used to deduct a payment of R299 every month every month up until I have finished paying for the contract,but it's shocking because even now I can't apply for another cellphone contracts because on the system it shows that I'm still owing a minimum of R600 which I don't even know😡😡I tried contacting you since 2023 with no help at all. You guys kept on saying that you will fix this and send me an email up until today. I'm not happy at all with your service its really poor.my credit score is not looking good at all because of you.