Pay Back my money and clear my name

I need your help or advise. I had an account with Cell C for years and everything was ok until the year 2020. My contract was due in April and I upgraded the account in June 2020 reason being I lost my phone in March toward month end. I decided to upgrade the account because I needed a phone desperately. I phone them and we finalize our renewal of contract over the phone and they activate the new contract as usual. For some reason they couldn't deliver my phone, said they couldn't allocate my address. But because it was Covid I thought maybe they used new courier that they don't know the place. I follow up with them but they didn't send me. until I phone them and they confirm that the parcel returned to them due to address not found. However they started to debit my account June Month end and I phone them to fix the matter or send me the phone they said the phone that i was looking for is now out of stock. I said I will wait for it. They debit my account again in July, August and September, I phone them to stop the account and close it. and cancel my order I don't need anymore but they couldn't stop the account or close it. in October 2020 I block and reverse their account being debiting my bank account. Then they keep on charging me and penalties for non payment. But when I phone them they were promising to attend to the query and resolve the issue but nothing. In December 2020 they finally accept to close my account with them. But still they promise to reverse the debit on my account and refund me the payment they were collecting from June until September till now they didnt. Now they handover my account to creditors Solution ***. But now they are ruining my name for nothing and I don't know what more must I do. As this issue is now affecting my health and my life. I need justice and I also need my refund from them. not sure where and how. If you can please assist me. Your assistance in this matter will highly much appreciated