Beating a greyscout IP complaint- counterfeit

I have received my first ever IP complaint from brand I am ungated with and sell their products, that brand is alleging that my products are counterfeit, they have made this claim without ever even seeing my product, I believe it was a automated system through greyscout.
I had bought this item in person from a TJMAXX brick and mortar store, and only have the physical receipt. I have submitted pictures of this receipt and of the product, only to be denied. My account health has been affected and I’m not to sure what else to do.

Amazon says I need:
A invoice (I do not have, I only have the physical receipt)
A letter of authorization saying I can sell this brand dated before the IP complaint (don’t have either)

To have the brand drop the IP complaint, I have sent an email to the company but haven’t gotten a response, what do I do?