Sounds like an untrustworthy dealer if I ever did hear about one. In my mind I’d be conscious of further issues with the dealer if I took the incorrect vehicle.
I agree it sounds like they’re trying to palm off a vehicle as your order, perhaps in the hope it could fix a private customers mistake. Perhaps the private customer changed their mind.
I wouldn’t accept the incorrect vehicle. It really does suck, and I’m sorry to read how poorly they’re continuing to treat you.