Mtn the Zone rosebank

It been 4 months now since I took back my phone to mtn the Zone rosebank the phone had a factory fault hence they saw it instead of giving me a phone they tell me about process that must take place mind u I use my own airtym to call they never call me for feedback when to collect my phone last month I got a message that my phone was collected from the shop so I call to find out is the new phone there no it no they still have wait and see if I can get a new one guys paying 389 month since Aug till now ist fair I want to cancel it I used the phone for a month then it been in their hand till today