I don't mean to be crass, but the question keeps replaying in my mind every time this thread pops up on "today's posts"...
Just zactly how did you and Mz. Renee crack the shower wall in the FIRST place!!??
That may help determine what kind of fix would be recommended. Like doin a fix and patch on the existing wall, adding a layer of anti fatigue matting, and then topping it with a fiber-fab sheet to match the existing panels. You should be able to move the corner pieces outward and it would still look practically OEM.
Only you would know he difference and we'll never tell.
On the serious side.. an over laminate might be the way to go for additional support and ease of installation.