The make of boiler and what it is doing is enough to start with. A photograph of the display helps.
Working across South Liverpool.
Placeholder: send your working hours and whether you take emergency call-outs, and they go here.
It opens WhatsApp with the message already written out.
Say the make and the code when you ring. Half of them point straight at the part, which saves a visit either way.
Depends on the age and what has gone. You get the honest answer rather than the expensive one.
Turn the stopcock off first, then ring. That stops the damage while you wait.
Your Gas Safe registration number, working hours, rates, the postcodes covered, whether you are insured and whether you do emergency call-outs are not published anywhere, so nothing is stated here rather than guessing. The Gas Safe number in particular belongs on a heating site, so it is worth sending first.