Bad Service from Mtn

Bought a phone at Sportscene Mall of Africa in February this year. Within a space of a month the phone started having charging issues until it stopped altogether. Took the phone in and I was told phone would be done in 2 weeks. Came back after 2 weeks and I was told phone is not ready. I then came back about a week later and was suddenly told the phone had water damage, this I got after MTN was called and was told of the water damage. I asked why did this take so long to figure out but no answer was given. So I asked for the phone to be returned. The lady promised the phone would be delivered in a weeks time and I would be called. My estimation is 2 weeks now since then and I went in yesterday and learnt the phone was not back. The lady at Sportscene called MTN again and was given excuses, I also spoke to Omphemetse who was so rude and told me that they would look for my phone and dispatch it. At this point I'm not sure if the phone is still there, it could be missing and all you get is excuses from MTN and its employees.