I have just returned from the local dealer, the rear driver side caliper had seized and has damaged the disc.

The good news is that they have managed to release the caliper and and no permanent damage just needs cleaning and refitting, the bad news the disc is beyond saving and will need replacing.

My question is that the cars is 3ys 8mths old but covered by a JLR extended warranty, i appreciate discs and pads are not covered by warranty as they are consumable parts but surely the caliper seizing has caused the damage and i'm now into replacing both rear discs and pads. The dealer has said this is not covered by the extended warranty, but would have been covered under the initial 3 year manufacturers warranty.

I am being unreasonable in thinking this should be covered under the extended warranty including the cost of the replacement discs and pads as this is not simply a ware and tare issue?

The warranty was sold to me as a fully comprehensive "manufacturers" extended warranty, i am now informed the warranty is provided by a third party on behalf of JLR

I'm afraid to say you probably have very little chance of getting this done under the extended warranty. Seizing callipers unless it can be proven it is some kind of manufacturing defect are going to be just put down to wear and tear. Even if they did cover damage caused to the discs, they would want a contribution for betterment.

Are you sure it needs new discs? - Main dealers tend to be a bit trigger happy on such things as they form the bread and butter of service items they make a reasonable margin on but to be honest new discs and pads don't cost that much anyway. I'd probably be grateful new callipers weren't needed as the cost of that would make me cry.

The Jaguar Landrover extended warranty is indeed provided by a 3rd party company (as are pretty much all extended warranties). It is provided by Car Care Plan and is branded under JLR.

How long ago did you buy the car from the dealer? if recent maybe you have cause to ask for a contribution from them ?