really ****ed off client of telkom

so I took out a cellphone contract through mondo for Telkom. the consultant advised that the contract for the hisense u962 is R99 on topup on Telkom. I agreed and took up the contract, when the phone came it was faulty kept switching off making lines on the screen I sent it back. they brought it back with no repairs done to it. since I took out the contract I have been paying RR350 to r450 every month and when I queried it they stated it increased to R149 due to vat increase but still I am now paying R450 every month and now all of a sudden the [phone is no longer on topup as per a sms that I received on wednesday. all I want to do is cancel this contract and I don't want to pay any cancellation fee as this is a **** service as nothing is communicated and when you call in you on the line for hours just to speak to a consultant which never happens.

I want to cancel this contract ASAP and I DO NOT want to to pay a cancellation fee. I want this sorted out immediately they can take their phone back.