Need Help

I have used to have a contract with CELL C ,in April upgraded with a Laptop which took a month to be delivered to me I then had to take it back to Cell C its now 5 months I still get billed for something I don't have, I phone them every month but no help their service is bad, I opened a case on the 30th August 2022 which the told me they will call me after 48 hours until now I'm still waiting for their calls, my Number is now blocked due to non payments because had to remove my money from my account all the time