Cellphone under warranty

My contract was due for update, got the new Samsung S7edge. In the c9ntract it state you have 7 days to report a fault with the device if you in counter anything. So i did get fault with the new device. I phoned both their numbers 4 to 5 times 4 days in a row . The numbers are *** and Cell nr *** and its was never answered. So i went to MTN the grove and Spoke to leroy and tild him the problem and inform him how many times i phoned to tell them the problem. Now my phone is out of that warrenty and my phone was sent in on the 26th of March and now its the 4th of April and still no follow up on whats happening. This is very unfair they way this matter is being handled. In my eyes this is not my problem nor my fault for them not answering their phones. They need to replace my phone with new one. This is the poorest servicei have ever received from MTN and have neeb with then for 15 years.