Does anyone know what this is? And if so, where I could get one?

We have had a back and forth with one of the "big box" banks. Our customer deposited an official check drawn on the big box. It has been returned to us "stop payment" prior to 90 days from issuance. Customer has been back and forth with big box, they have told our customer that we must send them a Holder in Due Course Claim Form in order for them to assist. They have also stated that 'they cannot assist you directly with the Holder in Due Course claim'. We have never had a request for this type of claim form in the past. We aren't even sure what information it is supposed to include. It just seems that the big box is making this as difficult as possible for our customer to recoup the funds.

Thanks so much for any direction you might be able to provide

I am not really sure what they are asking for either. But I am also not sure why the bank is injecting itself into this dispute. Your customer's claim is against the other bank. You really do not have a dog in this hunt. They need to get their own attorney involved and not the bank. You should not be providing them legal advice or assistance.