Horror subscription cancellation

I am struggling to cancel my LTE internet subscription with mweb since November 2018 they now want me to pay for the two months after I followed up why they still debit my account. After I informed them to cancel the LTE subscription they offered me another product (Fibre) different to the one I cancelled which I did not accept and was under no obligation to inform them since I have asked for the existing LTE subscription to be cancelled and I was not interested in the new product (Fibre) and this should not have any effect on the LTE cancellation request as it is two entirely different subscriptions and I have informed them to cancel my LTE product. I have today received a threat that they will hand me over to the credit bureau due to non payment of a subscription that I have cancelled and never ever used .