Hi
Are you saying this has done only 1400 miles? and the rears are shot?
I had the GT 170 when they first came out, did 18k in 12 months and had the fronts replaced twice.
I did have a problem to start with in so much as it felt wrong at the rear going round islands, turned out to be a tyre fitted the wrong way round from new, so they turned the tyre round but damaged the rim, on getting the car back I inspected the replacement rim only to see that it was tanished, they'd just swapped it off the demo! I never used that dealer again!
Anyway I can see the rear setup wearing a tyre out in 1400 miles when it took 7k to wreck the fronts on mine. the rears where never changed and they looked only about half worn after 18k.
Sorry to say this but in my mind there is something wrong somewhere and my best guess would be your dealer isn't telling you the truth!
If they thought it was going back to the finance company then i would say they had another used car in stock which needed front tyres and yours was the donor!