Advice on Coping Sealant?

We built a pool just over 2 years ago. The company found what appeared to be some very nice coping that matched - at least color-wise - our existing patio tiles. The material was described as 'slate', which it certainly is not. Rather, it's a thinly bedded mixture of siltstone, fine-grained sandstone, and shale. Problem is, exposure to moisture - particularly around the spa - is causing spalling, especially in those with a higher shale (i.e. clay) content. Thin chips are breaking away and of course are being washed into the pool. Over time, some of these have become 'welded' to the bottom, and no amount of scrubbing with a wire brush can get them off. So, my questions are two-fold:

1) Can anyone suggest a sealant which will both stabilize and waterproof? We have found Australian products called Dry-Treat 40SK (hardener and stabilizer) and Stain-Proof (waterproofing). These are quite expensive (approx. $2400 for about 180 sq. ft. in total). Do I have other options?

2) How do I get the pool bottom clean? Am I going to be required to drain the pool and acid wash perhaps? These little suckers are really stuck.

By the way, I am in a current BBB dispute with the pool company regarding all of this, but that's another story. A 1 year warraty on ROCKS??? Hmmm....

Thanks very much in advance.