First, review the contract you have with the listing agent in order to determine what kind of listing you have (Exclusive Agency, Exclusive Right to Sell, Open, etc.). This will give you insight on whether or not you can get out of the contract. Here is a helpful article about the various types of listing agreements:
Second, express your concerns with your Realtor if you haven't done so already. Most Realtors want their clients to be happy and should be accommodating if you feel their services have been inadequate.
Third, call their broker to try to resolve the issue, if necessary.
Hope that helps!
REALTORÂ® - lic #01923240
Certified Public Accountant (CPA) - lic #103885
Hammer Real Estate Group