Your vendor is probably already working with Red Sea, so I think you can just wait for that to happen.
In terms of your current tank, I would treat it as an extra tank, rather than trying to fix it to replace the damage. Let Red Sea do that part for you. This new tank you can just use as a spare, new one, or you can give it away to someone in the community. I'd vote on fixing it up for a future project or you can make it nice and sell it cheap to someone.
What I've seen people do is, remove the entire overflow box completely, and use a piece of glass to cover the whole bottom of the tank, new, so that the drilled holes on the bottom aren't exposed anymore. You lose a tiny bit of height in the tank, but it's small, and having a huge second layer of glass put in would be easy and sturdy. I've also considered putting down starboard over the top as well. The idea is, once that's done, you don't have to deal with those bottom drilled holes. Then you can put something like a ghost overflow into the back of the tank with a few drilled holes and you're done.