There are times when customers don’t understand how the scheme works and there are other times when dealers don’t. Neither scenario is good, but with the greatest of respect we have a situation here where neither party understand how it works, hence the car crash that you describe!
As others have said, you are under no obligation to take the car and IMHO you shouldn’t do so. The only exception would be if the car is right (other than the wheels) and you’d be happy to accept the colour, you could tell the dealer that as it’s their mistake you are prepared to take the car but won’t pay for the wheels – over to them! If they don’t, tell them to cancel the order, and go to a better dealer.