Loyal customer on the edge of changing service pro

Let me begin by stating that I am an MTN client in excess of 10 years. Unfortunately my most recent experience with MTN has left a sour taste in my mouth. I upgraded my contract at the Benmore Gardens store but since they did not have any micro sims, I collected this at the Northgate branch. At the same time I put a screen guard (Samsung S6) on my new phone (this was on 8/11/2015). During the next few days I noticed that every time I charged the phone, it heated up so badly that when it was charging, I could not even touch the phone. Hence I returned to Benmore Gardens, yesterday 14/11/2015 (within the 7 days) to return the phone. It was there that I had experienced the shocking service from both sales consultant and manager. A variety of incidents happened while I waited for more than 2 hours (note that I am 39 weeks pregnant) but the few that stands out is that I was given a total strangers documents (ID, bank details etc) when asked for a copy of my upgrade documents and also that because they had no stock, I was told to cancel my upgrade. I was also told that I was not be refunded the screenguard. In other words, its my problem, not theirs. I have therefore decided to change.