Bad service

My account was handed over Shapiro and I requested the amount in full, paid it off and they closed the account on their side. Called Cell C to update and the assured me the account was closed, they even gave the number to someone else. Months later I realize that I have an amount on ITC, I call in and same story, my account is closed.So I sent an email and got a reply saying they will call me within 24-48 hours. Time pass and no call nor email. I have been following up and I never get any reply and everytime I call they have escalated the matter. All I want is for them to update my ITC which should have been done seven days after payment