Hi , is the hot water working?
Do you have a wireless room thermostat?
The reciever is lit green?
Ok, first its important to verify it is a boiler fault and not the room stat. Within the boiler wiring centre will be the connection for the stat. Do you have the manual?
On page 29 is the wiring diagram for the stat. With the power off can you put a small link wire between 1 and 3 to bypass the stat ? This will confirm if it is a boiler fault or stat fault
Ok , to the right of the two big control knobs is the reset button. Press it in for a couple of seconds with the power on and hopefully it will work
Do you have someone who can help put the link wire in ?
no , unfortunately not . its possible it could be a fault with that as well
Ok , all the best . British gas dphave a set price boiler repair service. They will guarantee a repair for a certain price , parts and labour.