Cell C unprofessional and unfair treatment

Hi, i am not satisfied with Cell C. I feel like am unfairly treated. Paid almost 15000 for my laptop, it took them almost a year to allocate my proof of payment now they demand 9000 from me. I went to the bank sent them my statement as proof that they've been debiting. They just compiled the list and nothing was done since then instead i receive statement saying i should pay 9000. I've already paid since 2020 meaning i would buy a laptop which cost 7000 for almost 20 000. At this point i just want them to take this laptop and payback all they money i've paid coz i cant do anything as am under debt review because of them.