Are there any other VAG dealers near you, if so you might want to go with an alternate to the Karoq such as the Seat Ateca and VW Tiguan as 72Dudes suggested, same basic cars but different specs(bit better) and possibly some discount.
I would call Motability and tell them about the dealer lying or changing the contract and I would personally change dealer if that’s how they treat you and they haven’t even got the sale yet, how will they be once you have the car I dread to think.