Mobile network not available, Huawei G8

A

AC Question

I am using Huawei G8 and all of a sudden came across a problem, every time i try to call someone an error message appears on screen " Mobile network not available" though signal bars are there and I can use mobile data. Message sending fails too.
I tried different methods recommended on the internet to solve this problem even factory reset but the problem is not resolved. Contacting Huawei consumer support gave me very bad experience . Any help please?