Contract not Closed

I had a contract with Vodacom that I've closed in September 19 but to my surprise it's still showing on my credit report as a debt, I have called numerous times but no one could help me, I spoke to one of the customer care consultants and he told me that my account was settled but was not closed and according to him he is unable to call your guys accounts department to request them to close the account. That was the end of my conversation with him.

no call back no email.

account no I***-3 contract cell no: ***