There is no offer in your mail shot, it is the standard pricing available to all. The whole 2 for 1 'offer' has been that way for years and is like a DFS sale. Having said that, for what you get it is good value for money.
If you have an LS if would be £2,395, so by comparison you have a good deal. Certainly the bigger cars have the potential for larger repair bills but pricing is also down to parts availability (which are more available for the volume vehicles) and list price of the vehicle (and therefore what the owner can potentially afford).