Telkom refuse to cancel my contract even though it expired

I hav 2 years contract with telkom, everything was done telephonecally, they felivers the cellphone and all were good, at the end of my contract i called to cancel the contract and now Telkom doesnt want to cancel the contract seem i struck with telkom contract, consultants are rude and unhelpful, the service is no longer the same as i was takingvthe contrat, basically Telkom is refusing to cancel my contract even though it expired.Tht will be done only when i take a new cellphone with them