The web designers usually have a lot of different skills, but only provide specific ones to their clients. The issue is that often the communication of what is expected to be done on a project and what is not expected becomes obscure, especially if the projects guidelines have not been put in place.
It is important to be aware of what your web designer can provide in their services and not expect more than what the project has been agreed upon. Although the designer may do a few extras out of being nice or to make up for any inconveniences, it is not to be expected all the time.
Make sure to ask questions, and get it in contract on what the expectations of the end result of the project will be.
I have put together a graphic meme with a little on what web designers are not.