Acid washed pool, now surfacing falling out.

[Dee]

Our pool is just over 1 year old. We have had problems with constant staining. The builders acid washed the pool Jan 05 and again March 06. After this last attempt the gunite ( think this is correct) on our pool is just falling out. Every day we have piles of the blue fleck that was our pool lining drifting to the bottom. The grout between the tiles around the edges dissolves with just rubbing it with our fingers. It's like sandpaper beneath our feet and we are reluctant to even get in the pool. Our builder, says there's nothing wrong with the pool and just needs to be cleaned and they've called in yet another company for a cheap fix on the stains.
They keep blaming the pool cleaner, who we've used for years on several different pools.
We know this can't be right, we're loosing the entire surface. Can anyone suggest what went wrong and/or what can be done to salvage this situation.