contact them as motabilty will probably be fuming that the dealership has basically had you and them over, they have paid for a new car specced with sensors, these missing from the spec sheet affect the resale value of the car even at auction and motability have not got what they have basically paid for. Call them asap tbh.
and name and shame the dealers, this is so underhanded its unreal, keeping it all under cover to hide the defect as well as no parking sensors until after you entered the pin… some Dealers really get on my nerves with how they think they can get something over on disabled drivers…