Claiming I missed Payment when I have not!

I canceled my cellphone contract with Vodacom as I never had reception at my house. I then went on to pay as you go so that when I found a good contract, I could just port my number. I then moved over to MTN on a contract. I went onto Clearscore the other day and found that Vodacom has said that my account is still active and that I have missed payments... I was on a debit order with them so it would be impossible to miss payments! Also, I cancelled everything when I went to pay as you go and there was no outstanding balance.

I then tried to call the call centre and they could not track my ID.

Vodacom is now affecting my credit score when it should not be! Someone from the accounts department needs to rectify this immediately or I am sure there are grounds to take this as a legal matter.