I just spec'd my MY18 RRS AB to an MY19 and it is still £4550 more and I don't have massage seats

Sounds about right. I had to face an increase of just under 6k so dropped a few options but now it's dropped by 2k so I've added some back in.

So sitting at 103k instead of the original 100k on the nose.

3k for having the steering assist. Great! MY19 5.0SC Dynamic AB - Boss Grey, Black Pano Roof, 22” Gloss Black Alloys, Ebony/Ivory Massage Seats, Carbon Fibre Finishers, HUD, DTV and the all important Cabin Ionisation...