reached out to ford cs again yesterday about not receiving a letter. this time i was told to talk to the dealer
I was put in the same situation as you, didn't receive a letter, then running around in circles with CS and my servicing Dealer.
If this can help, here is what I did:
My dealer gave me a sample letter (attached), I modified the last page with my information, signed and mailed it in along with my Purchase Agreement.
Also sent a letter explaining that I didn't receive a letter from Ford directly, as they may have sent it to the wrong address, and to please use the noted updated address.
Letter sent Jun 17, received check yesterday Aug 24.
Truck was purchased Sept 2021