Debited account but no phone.

I took out a contract with Mtn for an IPhone, 2months into using the phone, it started giving me problems, home screen doesn't work nor can I press the home button, I took the phone back and the Mtn consultants at Westgate mall Roodepoort tell me they can't give me a new phone even though I have only been using the phone for 2months, they tell me they need to book the phone for repairs, I have been without a phone for 2months and finally after 2months the useless company call me and tell me my find my iPhone app is active I explain to them that I'm unable to login nor use the phone because the phone home button nor screen is working, to add insult to an already upsetting issue, they advise that I need to take the phone and send it to Istore, this company religiously debts my account without fail and I've been without a phone, I'm at a point of cancelling this contract because I'm really fed up with their pathetic service not to mention all the *********** staff they employ.