Bad experiance, and no feedback

Im having a bad experians with Mr Price Mobile. They sold me a phone on contract more than 2 years ago. The phone got ******, so I phoned in and told them that. They said I sould just go to the nearist Mr Price store and asked for a simswap. I tried to do that, but Mr Price here told me they dont have any phones or sim cards. So I decided to just pay the contract till its done, and that will be that. But without notifing me they extended my contract, and handed me over when I refused to pay the extended contract. Now they put me on credit beru without even acknwolaging my emails or any response from them. They keep on presuring me to pay for something I did not agreed to.