Does the contractor consider this finished? What stage of the project are you? If he just removed the forms there is still likely finish work to do. What is the final finish- are you doing a surface like cool Crete?

Looks like just a wood form was used for the pool edge.

A styrofoam form should have been used to create a variety of edges. The forms are removed once the concrete ii in a green state-not quite cured but workable. The edges are finished with special tools. And, it should overhang into the pool 2"

That job is unacceptable to me.

If Mystic Pools is correct you need to get two or three other companies to come out and assess the work and make recommendations (in writing preferably). Understand the process as well as you can so that you can have an informed discussion with your contractor. I wouldn't pay the balance of the invoice until you know what needs to be done and if your contractor will solve the issue. Make sure you document your concerns with the contractor in writing. Good luck with finding a resolution. Hopefully the contractor will work with you and find a solution.