Credit Bureau Listing

I have an issue with the fact that Cell has blacklisted me on ITC for an amount that I don't even owe. I call the call center and they advised that according to their system the amount is R4500 outstanding but the account has been handed over to Nimble Group. I then contacted Nimble group to make a payment arrangement and they advised that the amount outstanding is also R4500, however I was listed on the credit bureau for an amount of R8900 from Cell C, and no one can explain how they got to that amount.