Here's the situation so far. We went to LL looking at the bamboo flooring. We had concerns about it after reading about cupping issues online, but were assured that the new product didn't have that issue any longer. We had the Morning Star bamboo 1/2x5 Xiamen flooring installed in May of 2014, on an above grade cement floor (single floor house) that was 17 years old. We used the contractor working out of LL and through LL's HSS program. It's a glue down installation using the Bostik Seal-N-Grip adhesive/sealer (that was recommended as the best by LL and preferred by Morning Star). Within 6 months it was starting to cup at all the seams. We contacted the installer and he thought it was probably due to the humidity rise with monsoon season here in Phoenix, and told us to watch it through the winter. We contacted him again in April and he came out and looked at it again, and told us to contact LL's customer service dept right away, which we did. After their inspector, who wasn't NWFA certified, and our own independent inspector who is, finished their inspections, they both indicated the installer was at fault for not conducting a calcium chloride test (there was moisture between the concrete and bamboo), even though he (the installer) moisture tested throughout the installation process and even now during the inspections the moisture level was still within the spec. Needless to say we got a very nasty letter from LL saying they would do nothing for us.

We just know where to proceed from here. Do we need to contact our insurance company, lawyers, or who? Thank you for your help in advance.

Does the installer have documentation of the moisture tests? And which kind, CME (meter) CaCl or a relative humidity test? If not then he failed to perform his requirement. Call a construction lawyer. Have them send in a demand letter at least to get the ball rolling.
Unless your using an all in one - moisture blocking adhesive that has no limit and the slab was correctly prepped - as in grinding the surface to a correct profile then you dont have any idea how wet the slab was. I believe the limit on that adhesive is 85% rh or 3lbs with a CaCl test. Meters wont detect moisture way below the surface.