Overwashing can be too much for your hair especially if lots of products used and hairdressers usually wash and condition twice with quite strong products. If you've washed it again, it may be overkill and weighing your hair down in product.
They also tend to spend more time (or skill equates to more time as they're so used to doing it) drying and styling and they can see better as they have an all round view.
Take notes of what they did such as how they dry it, do they towel dry roughly or gently pat dry to avoid frizz.
Do they rough dry to a certain degree more and dry it for longer in general and do they style as they dry, what kind of tools do they use and how to they style it, do they pull it out and up and dry underneath so there's more volume?
Ionic driers are good.
Did they use any products like mousse or serum which helped give it that little bit extra?