How much has this pool cost you right up front? Look under the scope of small claims in your county. Look and see if they have a business license and if they are using legal workers to perform the work. Look under the secretary state website and do a business search and see if they have another dba or a corporation name they have listed. I know in Clalifornia small claims actions will be going up to $7,500, you may want to look up your state website. You may also file online as well. Look up the company and see if there are other people in your situation, if so, then I suggest you go to your district attorney. Or better yet TV works well, like we have channel 7 on our side. Some station that has the consumers best interest, and go to your local newspaper that also works great! I hope these suggestions would of some use to get this guy to either get moving on your pool or get your money back. Check and see if the person who ownes this company has property. Put a mechanics lien on his property, please look up your state laws on this.
Good luck.