I've had an issue with a Hampton Inn this week for which I've requested a refund for the night's rate or, alternatively, I would be satisfied with HH points in the value that the room could have been booked that night, had I done so instead of paying cash.

The area manager of the property says he is issuing a BMG certificate for a future Hampton stay and will not budge on an alternative option. I'm not happy about this because I assume it will have an expiration date, will require a more difficult booking process (phone reservation?), and is only available at a Hampton. If he won't issue a cash refund, then I think HH points are preferable since they don't expire and I can book online with any Hilton-branded property.

Are my concerns correct that a BMG certificate would expire at some point? How does one go about using it? We usually book day-of reservations while road-tripping, rarely in advance.