This is what I got from Air Tran
We understand the frustration that can result when a flight schedule is altered. When this occurs, we make every effort to best accommodate our valued customers. Our current policy allows the customer that has experienced a schedule change the option of being moved to another flight at no additional cost, or to receive a full refund if we are unable to find a schedule that satisfies your need for travel. However, there may be other options available to you as well. Should you wish to discuss your travel options, please call our Customer Relations Department at 1-866-AIR CHAT (1-866-247-2428). Our hours of operation are 8:00 AM - 10:00 PM Monday through Friday and 8:00 AM - 8:00 PM Saturday and Sunday. We are unable to modify your reservation via e-mail due to changing rates and flight availability.
In regards to finding a cheaper fare, the lowest fare is usually secured by booking in advance; however, on occasion, we will release seats at a promotional rate which may be more deeply discounted. As a gesture of good will, we will adjust the fare and the balance will be placed in a credit file with AirTran Airways, valid for one year from the original date of booking. Reservation credits are transferable and may be applied towards travel to any AirTran Airways destination. The new travel will not have to be complete by the expiration date of your credit file, only booked.