Cancellation of TELKOM SA services

I cancelled my landline as well as my ADSL in Sept 2020 with reference nrs and all. had to pay three months from cancellation of service according to their schedule which was done . Now they have handed over my account for over R7000.00 for services that has not been used to me after my cancelation of my contract with them. Is there anybody that can advise me what to do - I am not going to pay for services not received .