According to the official service schedule:
The 2 year 7500 service includes: replacement of oil and filter, plugs, and brake fluid. A throttle body sync. Also lubrication of the steering stem, and a while load of inspection items all of which are trivial.
We would argue that plugs are unnecessary but any dealer with his salt should be completing the service to the letter, unless he discusses with you whether he advises that certain items are unnecessary cost (such as plugs). If memory serves me correctly it's a 3 or 4 hour service at most.
I have seen dealers quoting as much as £16 per plug (Halfords charge £10).
Oil and filter is what? £60 at dealer prices
Brake fluid probably as much as £15
That's roughly £140
4 hours at £85 per hour £340
Any competent mechanic could do it for half that. Even less if changing the plugs isn't included.