Send what you have- within the rescission time window. Send it USPS Certified w/return receipt so you have notification that it's in their hands. Mark 'Rescission' on the outside of the envelope. It's all you can do at this point. They are not obligated to inform you of the progress of the rescission.In fact, I contacted the notary at their request.
After several attempts, I managed to obtain the contract number. Now, all I can do is wait and hope it's the correct number. Nevertheless, I'm following all the suggestions and adding all the data that can support the contract's validity. Time, ID, payment voucher, etc.
Regarding lawyers, I have contacted at least 5, but since I don't have the contract, they have been unwilling to take the case.
I think you'll be successful. Stay off the phone with them- especially if you think it's a salesweasel trying to change your mind. It may take up to 45 days to get your refund, but usually happens sooner. Obviously, you'll get the lost bag well before then.
Jim