I totally understand how you feel, as my order is scheduled for production in about a week. Since the bill was signed and approved by the senate, house, and POTUS, I think you are at the mercy of the IRS and their interpretation of what a contract is in your state. I don't believe a letter to anyone is going to change what has already happened.
However, what I plan to do is keep very good records of all of my interactions with my sales adviser. My situation is easy to justify since I had paid a $750 non-refundable deposit back in June in addition to the $250 refundable deposit. I also have a signed agreement that explains that the deposit was to be used as a down payment for the purchase of a specific mini model. Your situation may be completely different, but if you plan to take the tax credit on your 2022 taxes, you need to clearly document everything so you can submit it to the IRS if/when you are audited. You should also keep that $7500 somewhere handy just in case you need to return it. I am willing to take my chances.