Thickness of rotomolded products do vary, so not really unusual to see a variance.
The kayaks come with a two year warranty. We often make exceptions for issues out for few more years, but this sounds like a pretty old kayak? This is also at least second hand... so likely outside the reasonable period where we would be able to do anything in the warranty system.
There are a bunch of topics in the forums about repairs. One using DP8010 sticks in my memory as a thread with a bunch of good information.
https://www.hobie.com/forums/search.php?keywords=DP8010&terms=all&author=&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search