Cant use my MTN Phone

MTN, please can you get back to me as 90% of the time with full signal I CANT PHONE OUT. My phone makes wired sounds with im trying to phone. and the limited time i can phone my phone cuts the call off at around the 2min mark. This has gone on for a long time now and i have tried to speak to the call center but i cant phone out. my wife sits next to me and can use her MTN phone no problem. AND please don't ask me to restart my phone!!! I think you need to restart your network. Im awaiting your feedback