MTN IS STILL TO CANCEL MY UPGRADE, BUT I GET BILLED !

I have tried cancelling an upgrade which I had NOT RECEIVED THE SIM for, since december 2019. Now at the end of January 2020, Still no FEEDBACK FROM MTN, no cancellation BUT YET, I GET BILLED! MY *** and NO ONE until today has gotten back to me. How is MTN ABLE TO RUN SUCH A BUSINESS. I should mention ive been to two stores in the meantime, which took TIME, EFFORT AND MONEY, and guess what, same old reply..WE CANT ASSIST YOU AT THE STORE, YOU HAVE TO CALL IN. SUCH A HELP I MUST ADD!