I would bet that you will not get this tank replaced, Jebo is not the greatest at customer service and if you say the tank was level, I believe you, the slightest amount off shouldn't be enough to break in a year anyways. All my tanks are an inch higher on one side because they are on carpet in an old building, they've been sitting like that for over two years and haven't cracked and they were used tanks when I bought them. All-Glass used tanks, that is.
I used to have nightmares of them breaking but they keep on trucking, I'm selling them all for reptile tanks or use-at-your-own-risk fish tanks in a few months and upgrading to a 125. Hopefully they work with you but the store brushing you off right away is bad news, did it cause massive damage? That's a lot of water on the floor.