Could it be that the brake job includes new discs - I have seen it reported that because the pads no longer contain asbestos, the disks are made "softer" so that the pads do the same job. Also, it is generally considered that the rear pads/discs will need replacing long before the fronts because they are not used as much and any corrosion doesn't get rubbed off so they erode away quicker (see Honest John in the Telegraph). Even then, £500 seems a bit toppy for four brakes.
Anyway, I would expect brakes, tyres, etc to be classed as fair wear and tear and not covered by any service plan.
Having said that, I managed almost 80,000 miles in my X Type on the original pads and discs, and there was still plenty of meat on them. I've done 46,000 in the BMW - same story. Ditto Toyota at 55,000 miles (although it does have an electric brake arrangement which seems to help). I don't hang about either. The majority of my miles has been motorway driving though - lots of miles at 50mph on cruise control, giving ample time read the half baked notices that someone puts up.
Ian