[Dave G]

Report them to the local trading standards Jools,I did this to a local Kwik fit,turns out they were well known by trading standards for stuff just like this,it'll go onto a report sheet and even if no action is taken, at least they'll get hassle from it which will be a shot across the bows for the future.
This stuff goes unreported far too often,its deception and theft and garages should be brought to account for it.
My Kwik fit quotation of over £600 was sorted by a local garage for £80 including the MOT.