FAULTY NEW PHONE AND BAD SERVICE

Wow when you upgrade your cellphone -you expect to get a New (WORKING) cellphone. Well not in this case. I bought a NEW Sony Experia M4 Aqua Dual Sim 2 months ago and on the 2nd month I noticed that it overheats when I use it for more than 2 minutes.When I try to charge the phone top half became burning hot. Called Cell C and they advised that I hand it in for repairs and I did. They kept the phone for 3 weeks and I had to keep on phoning for follow up.On the 10th the called and said I can go get the phone.When I got to Kollonade they tell me that they are offline and I must come back again. I refused and they gave me the phone because they were lazy.When I got home I realised that the phone had the very same problem.It overheats and nothing has changed.I called cellc and was kept on hold forever,I sent an email but no response till today.Now we are sitting with the exact same problem. I am not happy with the phone and do not want to continue with them anymore.