That's terrible.
I don't remember if you answered this or not - was the concrete deck installed with a steel mesh bonded to the pool bonding wires?
At this point, all you could do is have a core sample pulled from the deck and sent to a petrography lab for analysis. If the concrete sample is shown to be defective (low compressive yield strength) and if there is no bonding grid in the deck, then you can make the claim in court that the deck as-poured is defective and, without proper bonding, it is an electrical safety hazard that fails the latest versions of the National Electrical Code (NEC) for pool construction. Determining that and getting a court date may make the PB realize that you mean business and are willing to go the distance to have this corrected. The improper drainage alone requires serious money to fix.
You may need to tell him that you refuse to make anymore payments and to stop work at the site until this issue is settled. He will try to scare you by saying he'll put a mechanic's lien on your home, but that's just a scare tactic. Depending on the lien laws in your state, it could take a lot of effort on the part of the contractor to get a lien and you can often contest them and have them dropped. In some states, if the contractor doesn't file a claim of damages with a court, a lien will expire automatically.
You should contact a lawyer ASAP to determine what your rights are here.
My condolences for all this stress, we all feel bad for you...