Number one mistake choosing web designers is a weak portfolio. You want to be able to see what the company can do for you. You expect that they lead with their best foot forward. If you look at their portfolio and are not impressed with what you see. It most likely that the work they will perform for you will not meet your expectations.
Number two mistake choosing web designers is chasing the lowest cost provider. Your quality will suffer and you may experience poor service. We all know that you get what you pay for. It is unrealistic to expect the highest quality at the lowest price. Does your business offer the lowest price? Price is one thing to take into consideration but it should not be your main deciding factor. If it is you may be very unhappy with the end result. You need to understand that you are putting the reputation of your company on the line and that your entire business is going too judged by your online presence. Sometimes we can do more bad then good without even realizing it. When you do realize it sometimes the damage has already been done.
If you are after a professional website that is going to deliver the results you're business is after then you need to understand that unless you have all the content prepared ahead of time that 2-3 weeks is not an unreasonable time frame. If you rush your web design company or they rush you there is a problem. It says that I don't care about my business and that I just want something up so I can move on. If they are rushing you then it says we don't care about your business and just want to move onto the next customer. These situations both have a negative effect on the final outcome of the project. To avoid this make sure you understand the entirety of the project and what is involved and how long each stage will take.
You keep spending time talking, but the person you are talking to doesn't seem to understand what you are trying to say. It might be that you are not you are not making sense or do not know enough about what you are trying to say. That doesn't matter! It is the web design company’s job to find out about your business and understand it. They should be asking the questions, not trying to determine what you are telling them you need.
How frustrating would it be to only find out the company you hired is only able to complete half of what you need? This would be extremely frustrating and could delay the project until you source out another company who can complete the work. Make sure the company you hire is able to offer a complete package.