Range from the cheapest Boiler service £50 (WI Gas Services Ltd based in CR0) to the dearest Boiler service £180 (1977 - Denham Plumbing and Gas based in SE26).
Comparing heating engineers estimates for a Boiler service gives you an idea of who will be better value but the best way to compare costs is to get actual quotes.
What to do - Get rates and quotes for a boiler service by posting your job to heating engineers in SE19