CELL C - cancellation of contract - IMPOSSIBLE

I have been with Cell C for many years. However, my contract stopped in 2016 but I never canceled it...The debit order just keep on going off every month...until a couple of months back. As I am being retrenched, I want to cancel my contract just to find out that my debit order did not go off twice...Upon further investigation, I find that Standard Bank closed my account as I did not use it. I pay the R130.00 (12/05/2020)and after a few days called Cell C again. By this time, it was the new month. Now they tell me that I need to pay another R130.00 (2nd June 2020)and then call back to cancel. For the past week I can not get through to them...Eventually today, I get hold of them, told them I want to cancel...but because I can not tell them when my debit order runs, they tell my the info I give them is incorrect...I gave them my ID nr, my name, my current tel nr....but NOOOOO - I failed the security check! Now I get told to go to Cell C store ( where I was in the 1st place & they told me to call and cancel) I demand to speak to a supervisor and so I was put on hold for like FOREVER! I eventually after about 10 minutes put the phone down, MY QUESTION NOW IS _ HOW DO I CANCEL MY CONTRACT? Next call they will tell met to pay again? I have not been using this phone for YEARS!!! I JUST WANT THEM TO CANCEL IT - IS IT THAT DIFFICULT TO DO????