...in my house.
RANT ALERT!
Yes, the poxy boiler's gone South again.

Had a problem a few weeks ago with the reset button light coming on every day. Called in an "engineer" who said he could find nothing obviously wrong but said he serviced it (I was out at the time) and charged us £100. Problem got worse.

I changed the diaphragm, then the ignition module. Still the same problem, with the hot water tap running hot, then cold, then hot again and the reset light coming on more regularly.
Cleaned out the secondary heat exchanger and I thought it worked a bit better (wishful thinking?), but only for a few hours.
Changed the thermister. No improvement.
Now it's started playing up on the CH side as well. In fact, the boiler won't ignite for either central heating or hot water and the reset button stays solidly on. Tested (as per the manual) to make sure I'm getting 240v at both the PCB and igniter - all OK.
I am guessing it must be either the PCB or the gas valve, but that's it - just a guess. I can't and won't touch the gas side, so it looks like a freezing Easter and another £100+ next week for a gormless dope to tell me "Nah, you need a new boiler, guv".
Just 17c in the house and falling. Time for another sweater methinks.

RANT OVER!