I think this is total urban legend.
When the car comes, it has the build sticker with all the options. If the options are listed on it, you pay what was originally agreed upon. If those options are missing from the sticker but have been added in the car, then you have to pay for your impatience.
Has your dealer called you to offer you this or are you just listening to morons? If they did call, you simply say "Ok, cancel my order. I'll be down to collect my deposit....I'm getting a Mustang instead, they have exactly what I want on the lot".
Or find the car somewhere else.