What would you do in this situation?

I've been trying to purchase a horse since early spring with no luck. I've had several with disheartening settings. I recently found a horse that fit my requirements from a reputable adoption agency- one my trainer got her personal horse from! My only requirements were 17hh and the ability for light jumping. I'm ~6ft and all leg. While I will ride any horse i can comfortably/safely ride, for a personal horse, I really wanted something taller.

The horse was listed at 17h. He had a free movement and lunging video. He looked huge & great (I guess the lady was extremely short). I got a vetting done with an unbiased vet, not associated with the barn. I gave her a list of things I wanted to see/confirm, height being one of them. She said the horse was huge! When I got the report back, he was noted to be 17.3. I was surprised. The owner got back to me and said she thinks the vet sticked him wrong. He is 17.1 max. I was fine with either or. I paid the purchase price & booked a shipper.

I got the horse today and I was very surprised how small he was. I was able to almost wrap myself around him. I pulled him out with my trainer and she sticked him. He JUST hits 16.2 standing square on the pavement (with shoes on). I was extremely disappointed as that was my biggest requirement. I was also genuinely confused how a vet could get the height THAT wrong- how can I trust the rest of tbe report? I immediately contacted the agency and told them I was a little disappointed with the height. They then said "no, he is 17 hands. The vet even said he was 17.3". I plan on going out to the barn and getting photo proof. He's also not a thick build either, which doesn't help.

What would you do in this situation? I feel so disappointed. I would be fine if it was slightly off, but 16.2 to 17.3? How?! I unfortunately can't keep him and get another.