Billed for internet usage without having a landline or ADSL.

On March 2017 I cancelled my landline and ADSL with Telkom due to poor service. To date i still receive invoices for internet usage. Despite numerous phone calls, visits to local Telkom offices ( where e mails were sent on my behalf) we have now been handed over to debt collectors. Not sure what else to do!!!!!!!!!!!!!!!!!!!!!!!! When you create a dispute they supply you a reference no via sms then when you follow up they say there is no such no and they create a new dispute no. Frustrating is not even a word to describe it.