haha, yes the old safety check. Went to a logic that had been serviced for 3 years in a row by a so called service engineer, i took case off and spotted daylight / a hole in the case where a grommet was missing. not a good safety check if you cant even visually check the boiler is safe to use...
get a fitter with a thermal image camera to check for heating circuit, if its in the way drill some holes into the tile only and fix pan down with strong concreate mix, half a bucket should do it.
logics are a very good boiler, only issues i found is following so called engineers who service them without even opening the case, this is the same with all other boilers aswell.
is it a combi for combi swap?
to many things influence the cost apart from the boiler itself even if you had a not very good boiler like a vokera....... gas upgrade, powerflush, controls, filter, flue system, condense route etc......
Did the powerflush take all day? What chemicals were used? What pre and post survey paperwork was left? British gas won't guarantee much after powerflushing but they should do a proper pre and post survey at least.
Sometimes the only solution is to renmove the badly blocked paperwork.
no idea of what hourly rate you would pay, remember an hourly rate is normally based on a full days work.
you will need the gas safe engineer to disconnect the hob if your changing the worktops/ kitchen which will involve another visit.
if the vessel just needs recharging then the cost should be 1 hours labour. this can be done on an annual service so maybe book a service if it has not been done in last 12 months but tell the engineer theres a pressure loss issue.
tell her to ask the engineer who does the annual service to check it out. as above its possible an expansion vessel, prv issue. if she has not had it serviced for a few years it probably needs an important seal changing.