Dispute

I was given a telkom day sim via online A day after receiving it I realized I don’t have the coverage I phoned them ,gave out my address yes they confirmed that my area doesn’t have coverage They adviced me to send an email to cancel the contract I did they even confirmed that it’s cancelled to my surprised this year I got a notification from transunion that I owe telkom 9 months and my installment is 670 ,I phone them and I have spoken to Shongeziwe somahe she told me I have to pay 400 for the usage I asked her what usage Coz my are doesn’t have the coverage

I loved a dispute with transunion,after 20days I got an email from them that they removed my name as telkom failed to send a proof They now blaclisted my name with Comp**** I really want them to prove what is it that I owe them that they can even blackist my name I want them to remove my name ,I have bunch of emails with case numbers that shows I have cancelled their contract