Part of the challenge of the real estate business is setting correct expectations with regard to the sale of someone’s most valuable asset. Often, this is an asset that the owner is emotionally attached to and is really not ready to sell.
Why Are You Unhappy?
Are you unhappy with your agent because they are not returning your calls or emails? Or did they ask you to fix something that can potentially turn away a potential buyer? The first is a legitimate concern while the latter is part of the home selling process. 
Your agent should be responsive to your inquiries. Do they respond to your calls and or emails? Did they explain the agreements to you before asking you to sign them? Did they communicate proper expectations regarding showings, negotiating offers, and home inspections? A good agent will cover these points thoroughly.
Communicate That You Are Unhappy
Communication is key. If you are unhappy you need to let your agent know why you are unhappy. Many times conflicts arise as a result of a miscommunication. There are a lot of steps in the home selling process that can be stressful. Call your agent and speak with them about what you are needing that you feel you are not getting.
If you have tried to communicate with your agent but have had no progress you can contact the Broker In Charge. Every firm in North Carolina must have a Broker In Charge that is responsible for compliance with certain regulations and is accountable to the North Carolina Real Estate Commission.
If this doesn’t work you can try the principle broker. This is usually the owner of the firm. The good part about real estate is that the principle broker goes to great links to advertise themselves so tracking them down should not be a problem.
Also, if you have hired an agent that is part of a large franchise you can contact their corporate office if you are unable to get a satisfactory resolution at the local level.
Look At Your Agreement
It goes without saying that you should read your agreements before you sign them. However,depending on your state, the agreements can be several pages long and are quite complicated. What is the duration of the agreement? Is there a termination clause? 
Since real estate brokerage is very competitive, I have seen buyers and sellers be let out of agreements if the relationship is not working. A successful real estate transaction requires everyone to cooperate and have realistic expectations. However, don’t be surprised if the agreement grants the real estate firm exclusive right to represent the client of a given period of time.
Request A Termination of Agreement So You Can Move On
Depending on why you are unhappy, you can always try and get another agent within the company to represent you. This can be a great option if one of the agents is over-worked or you are just not getting along.
If you are deeply unsatisfied with the company as a whole you can request a termination of the agreement. It is best to get this in writing.
Complaint to a Regulatory Body?
I’d save this as a last resort, but if you were extremely unhappy and have not gotten anywhere with any of the resources above there is still the remedy of a regulatory body. We have the North Carolina Real Estate Commission which regulates general brokerage activities. A written complaint will result in a mandatory investigation and will definitely get the attention of the real estate firm.