If you have the most recent style of light duty, you can use a flathead screwdriver to bend the metal tabs outward when the shelf is in place to give it a snug fit. Don't go nuts with it, just provide enough force so that the tab is actually pressing against the upright, preventing it from lifting out of place. If you want to move the shelf later, you can just tap a mallet on the corners to bend the tabs inward again.
Make sure they're actually right side up as well. I've seen too many people put them in upside down.
If they're too badly damaged, as Dysprosed mentioned, you can get your ETL to order new shelves. They're actually orderable again, though with a 50-ish day lead time. Or if you have a decent PML, just mention the shelves to them (or submit a work order) and they should be able to do what's necessary to fix the problem.
Or, if you're rather brazen, consider the shelves a "safety concern" and utilize Origami Risk to try and "force" a solution (this is a gamble; you could get new shelves or you could get those sections taped off so that no one uses them -- depends on leadership, your mileage may vary).