Corroding walls behind vinyl liner

[Danomite]

We have major wall corrosion behind our vinyl liner (in-ground pool). I've pulled away much of the liner and can see the bad rusting/corrosion. I've been told by a couple vinyl pool guys that we basically need to start over and rebuild a new pool.

It seems that surely it couldn't be this extreme.

It would be very helpful to learn from anyone's experience with something like this.