Cell c refuse to terminate contract after requested to cancel contract after it ended!!

I was always a loyal customer to Cell C and HAVE ONLY ONE CONTRACT WITH CELL C. My contract ended and i phoned APRIL 2018 to cancel my contract. They have found the recording that i requested to cancel my contract but now they come with stories I did not specify the cellphone number that must be cancelled. I AM SO UPSET BECAUSE IF I HAVE SIGNED MORE THAT ONE CONTRACT I CAN UNDERSTAND BUT I REQUESTED THEM TO CANCEL MY CONTRACT AND TILL TODAY THEY KEEP ON DEBITING MY ACCOUNT AND I HAVE PHONED NUMEROUS TIMES, driving to the bank each month to cancel debit orders and going to the store. THIS IS TOTALLY UNACCEPTABLE FROM CELL C AND I NEED SOMEONE TO HELP!!