You had 8 years (maybe almost 9) to use the cert & didn't. Have you not checked your 'Marriott file' in the last 8 years, so you could use it before now? I think you're asking a bit much to expect them to honor it. So for this one I'm siding w/ the property.

If you truly want to pursue the $109 value you'll need to do so back in the US IMO. I can only speak for myself, but I'd let it go. 8 years is a long time to expect any entity (airline, restaurant, retailer) to honor a certificate. It's not their fault you took so long.

Cheers.