Who to contact if smart meter fails

[moonlight]

I have just been round to a customers as they have fault on their boiler. Turns out they have no gas. There is gas at the incoming valve but nothing going through meter. Who do they contact? Thanks

 

[ShaunCorbs]

Supplier / who they pay the bill too

 

[snowhead]

The battery has failed in the Gas meter, not uncommon and will be more common in the future.
New meter required.
The "Smart" or not so in this case, Gas meter communicates with the Electric meter using battery power.
The Electric meter communicates with the Data collecting centre using mains power.