s3 issues no signal and no service

[Amanda30Ro]

hi
I recently had my daughters s3 screen replaced but since then shes keeps getting no service / no signal a lot of the time is this something that was done when the screen was replaced ? she has a young son and lives alone so worry this phones not going to work in an emergency should she need it to, is there anything we can do to restore the signal without taking it to a shop and pay stupid money to get it fixed ? :-[
weve tried a simswap as suggested by orange but that didn't make any difference

 

[Nitesh37]

You need to check your handset imei no. by using *#06#. because of mistake in imei writing this could be possible .

 

[Amanda30Ro]

ok thanks I will try that,
It doesn't do it all the time tho but a lot of the time so could that still be the problem ? sometimes it cuts off during phone calls too

 

[Amanda30Ro]

the imei number is correct