Something similar happened to me, I was expecting the car to be delivered end of Feb, with a registration on 1st March, but got a call from the dealer saying it was here, and to come and check it out.
when I did so I noticed that the car had already been registered on a 74 plate, when I said it has come too early and I do not have the AP, he said how much short are you.
£500, so they dropped the AP by that amount.
might be worth a try, if you are paying any AP.