Emergency calls only

[whirlwin]

I have had my Nexus 4 for some months, but just recently it is unable to make use of any of my SIM-cards.

I have tried different SIM-cards (that previously worked on my Nexus 4 and works in other phones from different providers) and a brand new one, but it keeps showing "Emergency calls only" with the Nexus 4. I have also tried connecting to different providers (in the UK), but with no avail. I also tried a factory reset of the phone.

Is there anything else I could try? If not, is there any way of contacting Google, or LG by email, and not by phone?

Thanks in advance.