Returned damaged phone

I bought a phone on credit at Markham in March this year... within 6 months it had technical problems, the escape button was not working, I took it back to them for repairs, 3 weeks later they call me to come get back my phone, I get there to pick it up only to find that it's still not fixed.... the guy I spoke to apologized, said that the people at the repairs didn't know what's wrong with the phone, but now since I have explained to him what's wrong with the phone, he will take it back with the correct fault details, within 2 weeks they will call me to come get the phone.... after 3 weeks, they still have not called me, I go there to check with them, they tell me the phone is still not back wara warah, I throw a fit and ask them what must I do now bcoz I don't have a phone and they are unconvincing me, and I threatened them with cpa... that guy by the name of Siphiwe Mpanga tells me to go to cpa it's fine, I requested to speak to his manager, he said his manager is not a available. He then says to me that he will call the people from Vodacom and ask the progress with the phone, the next day he will call me with the progress. After 15 minutes I had left the store and boarded a taxi to bara, that guy calls me and tells me that sorry the phone is at the store I must come back to get it, 15 minutes after that he calls me again and says the phone is still not fixed . I went to hello Peter and wrote my complaint there, instead Markham just rep**** to say they will soon get back to me, even now they have not kept to their word.