Waiting for feedback from mtn it been a month now without my phone

On the 6th of January I upgraded with mtn at Eastrand mall Boksburg , I took Sony ultra it goes with a volcano speaker it was for free. Then Sunday i saw that my phone was having a faulty at the back of my phone they were bubbles the battery wás busted then on Tuesday on the 9th of January I took it back to East rand mall Boksburg, When I arrived there I was helped by Vusi then they took my phone and said to me they will call me within 7 to 14 working days even now I 'm still waiting for my phone, they expect me to pay for something I dont have. All i want is a new phone