cancelled my booking eventhough I payed my ticket within the cut off time.

I booked a plane ticket through Travelstart on a day that they where running a special and payed it before the cut off time that was emailed to me. The next day I receive an email stating that I have to pay extra as the fare has increased. I emailed refusing to pay the money as I payed my ticket in time and the fare can't increase if it states that the special runs until midnight. The next email I received was that my ticket got cancelled. After complaining at customer service, I receive a general email. I rep**** with my concerns. After about 2 emails which where in no way an attempt to help out I stopped receiving any feed back. It has been 2 weeks and I has not received a reply or a refund. I have recommended Travelstart to a few people as I have never had problems before but this will definitely change my mind of using them again.