Technical Connect nav+ phone problem

[Little Ghost]

Hi all. Got an annoying problem just started happening on the connect nav+ on my Stilo Abarth. Tried to make a call the other day and it just kept saying call in progress for ever. Satellite level is full but I noticed where it usually shows my network it just says "Find..." pay as you go sim, and have had no problems up until now. Anyone had a similar problem before I try another sim?

Thanks
Alex