Very poor service from CellC customer service

I cancelled my Cell C contract a year or so ago, because of bad service delivery and undeclared debit order amounts. Now they listed me on experian for unpaid fees. I phoned them to find out what the fees are for, and they said that according to their system, my account has no outstanding balance. So they said I must phone the legal department, I've been trying that for 3 weeks, and simply just can't get through to them. Then they said, send an email, they don't respond to that. I'm so fed up with cell c. And I'm not the only one in my family struggling with them. They are seriously useless network providers and beyond poor customer service.