I'm sure that OEX can fix it for you. You could probably do it yourself if the holes weren't too badly mangled. Rivets usually bend back a little if they get pulled. From my experience, they usually just leave a slightly larger hole with some jagged edges. If there was no major tearing of the plastic you should be able to put the flush mount back in. Make sure you use a gasket or a good bead of 3M 5200 or Marine Goop. Use stainless steel bolts with a washer that is wider than the hole. Better yet; get a strip of aluminum, drill a couple of holes in it that match up to bolt holes and use that as a backer.
This backer plate for my flush mounts is a little bit excessive, but you'll get what I'm talking about.
I pulled the flush mount out, re-shaped the hole, turned the holder 45 degrees, did a little plastic welding to fill the gap and re-installed the holder. The backing plate makes it stronger than the original set-up. Anytime you can use a washer or a backer it will be much stronger than just a rivet. I use these short pieces of aluminum C-channel as backers on some of my RAM rod holders. The nylon cable clamps give me convenient places to zip-tie cables to keep them out of the way.
