CELL C - ROBBING ME BLIND

I have been complaining about my cell phone contract which was supposed to have been cancelled in 2020 and I am still being billed for a contract after I returned the cell phone a day or two after it was received. However, Cell C Claims they never received. I received a quick response requesting me to send in all my evidence (i have messages stating that my phone was collected and in for checking); (I have a picture of the van and person who collected my phone); I have e-mails of me enquiring if the contract was cancelled and their response, but have heard absolutely nothing about my money being refunded. WOW CELL C YOU ARE A DISAPPOINTMENT AND WILL NEVER GET A CONTRACT WITH ME AGAIN!!!!