cancelled contract - but still paying.....

My data contract expired in March 2021 with Cell C - to which no one from Cell C contacted to inform or offer a new contract to.... I called in in April after they doubled my monthly payment and cancelled the contract which they then said will end on the 19th May. they contacted me and confirmed that the R320 of end April would be the last payment - now in May I'm getting billed again for a contracted i don't even have?????????

Worst of all is when you call the call centre there is 10 000 excuses and reasons why they want to keep on deducting moneys????