If this goes south, you'll appreciate what Kim advised earlier: everything in writing. Meetings at the pool are a necessary evil, but if you're not communicating exclusively in writing, you should do one or both: have a third person present, a witness. Non-spouse, non-relative is best. Whether that can happen or not, don't just "shoot the stuff" with the contractor. Outline your questions and concerns before hand. Be methodical. Be prepared. Take notes during the conversation. And/or have your third party do that. That can be a bit counter-productive, and can be off-putting, but, IMO, you're accomplishing two very important things: you're accurately tracking, in real time, what is being asked and answered (which you won't be able to do comprehensively even a few minutes after he leaves), and you're sending a very clear message that you're not messing around, that you're not going to get pushed around, and that you're gathering evidence.
Again, this can be off-putting, but that's my MO. Not everybody agrees with that, or has the stomach for it, but it was absolutely instrumental in how I won my new finish. After the first couple conversations with my contractor went nowhere, I ceased all verbal communication with him and insisted on everything in writing. I used certified mail. He did too. On several occasions he incriminated himself (these guys are generally not to savvy when it comes to this stuff), all in writing, all certified. He continued to stall and make up excuses. I had the pool repaired by another contractor and then I ended up just turning over all the letters to the contractor's board. A few months later, I got one last certified letter that included a check for the cost of the entire repair...