They aren't all spivs. Our heating broke down the other day - oil boiler, rural location, 8pm. Rang a heating engineer, got us to push a few things, try this and that and diagnosed the faulty part over the phone. He said he would be there 7.30 am the next day from 10 miles away. Arrived on time, with part, fitted it, tested and all working within just under an hour. Googling the part its ã25 - 30 from the plumbing supplier I know he used, not much cheaper from unknown origin flea bay type of places.
Invoice was for ã84 inc VAT. Seriously good value if you ask me.