Bad Service and Unfair Practice

I had a contract with Cell C with a R299 deal for 20/20gig, Paid for a year and half. After 11 months of contract they started debiting R372 and when i call and ask why they said its late payment it went on for 5 months and when i complain same excuses but my bank account always have enough money i called and ask to pay for the whole contract st once, they said its not possible.

Then they introduce a new deal when i was calling to cancell my contract the new deal was for R289 per month with 30/30gig of data, The consultant by the name of Sphiwe promised to migrate me to the cheaper contract yet more data, After 3 days he called to confirm that the migration has been approved it will be effective by the end of April, But i should pay sum of R420 settlement yes i went to Nedbank and pay. He called after two days and confirm the settlement is in and he started to read me all the terms and condition of the new contract, all was perfect and he told me on the 1st of May i will be getting my 30/30gig data. Comes the 1st of May my modem is not working i called the call center they told me my contract was cancelled and now im on PrePaid. Then i called several times they said they cant help me , OK i gave up, The the problem begins every 2 weeks Cell C is debiting R136 twice a month since May 2019 to date they *******ly debiting my money without my concern