I get your points that it's worth doing then.
But why not put it on the service plan if it's so important. that's really annoying, I bought a service plan so that there were no hidden extras for the next 3 years. 
To answer your point.
I asked my dealer a month ago and was told it is part of the service plan so perhaps try another dealer? I think they are not entirely consistant and as its not an uncommon mass produced car plenty of dealers around so try another, but make sure its from a different network (not two inchcape or Marshals or Marriot group dealers etc).
But if not, brakes and tyres, brakes and tyres, don't be a tight arse and pay up

Its about the price of a tank of fuel which we happily through away on pointless journeys