Well, did you have a written contract? Did the contract contain one or more images of what you expected? Did this fellow have references? Did you visit any of his references for exposed aggregate jobs? Have you paid him? (If so, why!)
I've had fellows promise this and deliver that - but they do not get paid for labor or materials if the work is not done as promised and described in the contract we sign before a spade is put to earth.
Last guy agreed to do a drive with X tons of large rock and Y tons of ABC crusher run for Z dollars. After he left the gravel delivery driver called me to say he hadn't been paid for a load (or two). I advised him that I'd paid the contractor in ful and had the canceled check (image) to prove he'd cashed them. I also showed him a copy of the contract.
He said "I never would have signed such a contract."
I replied "Well, then, you would not have gotten the job."
Unfortunately, if there ever was a time when a man's word was his bond, it's long been over and your best protection is a written agreement and payment upon completion per the the agreed terms.
Also a good idea to read up on the work you're wanting to contract out so you might more readily spot the phonies who think the bedrock goes on the drive last - or what you got is "exposed aggregate" because "You can see aggregate!"
Remember, there's a sucker born every minute.
You are being a little hard on the man aren't you?
Contracts and written papers are one thing but the end results are all that really matters. On small projects like this, all the paper in the world is not going to fix something like this unless the guy that did the job is willing to admit his mistake and fixes the problem on his own.
The problem with concrete is there are too many variables that can take place on a small job like this. Weather, site conditions, problems at the batch plant, hangovers, and there are those that are out just to make a quick buck.
Most all of the really good concrete contractors out there won't even look at a small job like this, they want 100-yard or more pours before they will even talk to you.
There are some good small job contractors out there, but they are hard to get because they are so busy and book months out. People are pretty much the same all around and when they decide on doing some project, they want it done now and that is when they turn into fish and believe me there are a lot of shardy fishermen out there.
Pretty much all the small job concrete finishers I know want you to pay for the concrete up front, (they have been burned a time or two also). All they are doing is supplying the labor to finish the product you have bought. Most all of the finishers, at least in my area charge for labor the same as what the concrete cost and if you have site work, they charge extra for that. If you do your own base and form work that adds a few more worms in the can to wiggle out of in case something goes wrong, and someone tries to take him to court.
All this really means is that no matter what you do there will be no guarantee of the end results. It should be but in today's world you never can tell anymore.