I think that they should at the very least contact the individual customer with an "approval of changes" form to sign off on. That would allow the customer to agree or deny to the deletion of those items. If they don't agree to it, Ford can put their order back in que and find someone who doesn't need/mind those items being deleted. (some would rather wait on certain items)
A purchase order with a deposit is legal contractual agreement. Ford has no right to unilaterally change that contract, even if they do offer a discount.
This is like McDonalds offering Big Macs without the two all beef patties, but giving us a 40 cent discount. What's the point?