End of Contract

My contract with Telkom ended on the 07 May 2022, but I still recieved a bill that I need to pay R99 end of June, when I called the call Centre I was told that if I don't pay, I will be charged penalty fees if they can't deduct, she further explained that they don't automatically discontinue they're contract, which I had already made them aware in April that I will NOT continue with they're service when my contract ends, a case was logged for me and promised a case number which I still haven't received. I am very frustrated as had to take my take my time and make multiple calls without a solution.