I can't make call with my line

I just subscribed for the MTN CUG about 2days ago. Ever since, I have not been able to make and receive calls. I even tried calling MTN customer care line to relate my complain...

I moved to UK recently and since then I have not been able to make calls to Nigeria. I do receive calls though. What could be the problem.

I can't receive or make calls why?

I can' make calls since two weeks...