If you know anyone else who was cheated by the same vendor, urge them to do the same. The event organizer is not legally obligated to help you get satisfaction, but may be willing to do so in order to keep your goodwill with respect to her event. Send a letter of complaint to the Better Business Bureau about the vendor who cheated you. If you know anyone else who was cheated by the same vendor, urge them to do the same. Tell everyone you know that you have been cheated by this vendor.
Word of mouth can be powerful.
Send letters to all sponsors of belly dance events that you regularly attend alerting them to how this vendor has cheated you and urging them to decline any applications this vendor may make to appear at their future events. Tell that that you're certain they wouldn't want attendees at their future events to be cheated by this vendor the way you were. With her permission, I included her advice in this article, and then added to it from my own knowledge of business. Scheherezade Imports is a reputable business which has been delighting belly dancers with its merchandise for many years.