they are pants! We didn't have cover with them but they advertised that you could still have one of their engineers come out within 48 hours. We rang booked appointment and guess what no show! waited in all day, as like you had small children and heating in Nov. British gas are just pants, we ended up waiting for nearly 2 weeks with no heating.
Ring them back and tell them you are calling the papers and do they really want a story about how they've left (a widow - do you want to mention this - the papers would lap it up but it's up to you) little children in the cold, in the news right now when they're trying to justify huge bills for consumers..
My boiler gave up the other day and I fixed it myself. I googled the boiler name and followed the instrutions. The power switch had tripped (unbeknownst to me) and the pressure had dropped. I got the pressure back up and then realised that there was no power. Flicked the switch under the stairs for the boiler and hey presto! Sorry if you've already tried this but worth a post.
A collegue called them out on Boxing day last year. They couldn't even send an engineer until the follwing Thurs (I think boxing day was Sat/Sun IIRC). Engineer couldn't fix it, ordered parts and they had to wait until the middle of Jan for them to come back and fix it.
I have cover with a local plumber. Costs me about £120 per year (which I think is a fraction of BG). They come and serivce annually within that price and the one time I have called them they were here within 2hours (and it was an evening call). They were not able to fix it there and then because they needed a part which they couldn't get at 8/9pm. But they had fied it by lunchtime/early afternoon next day.
Obviously I can't recommend them because you are not local to me. But I do recommend finding a local recommendation.