Cell C is a *******

I am so disgusted in Cell C. I took out a contract in 2017- it expired in 2019. They then called me to say I owe them almost 7000 rand and handed me over to debt collectors. I paid the money over the years and now that I'm done they reactivated my account and I owe them now once again keeping in mind that we are now in 2022 and I no longer have the number nor the phone. So I paid the addition R239 that I now owed them for last month. I was told to cancel the contract so I phone to cancel the contract just to find out that I can't cancel it because I fail the security questions. I feel this is a *******. I have paid Cell C since 2017 and still paying. Apparently my ID number, name,address and email address is not enough. I now have to remember what date I use to have the debit in 2017. Cell C is sucking the life out of me. I am stressed and I cannot believe that I must continue to pay because they can't cancel my contract... this is just outright ******ion.