Changing the TwentyTen Header plugin

My site is avelim.co.il. The site is on Hebrew wordpress 3.3.1, using the theme Weaver 2.2.6 with many customization done by programmers. The site uses the plugin TwentyTen Header which was further customized by a programmer. The plugin allows to set a different header image for a category (pots and the category page of that category). There is one issued I want to solve: The situation - a post is under several categories More than one of the categories has a header image defined in the plugin Currently, in such a case the plugin chooses one of the category header images arbitrarily. I want this changed. I want that in a situation that a post has more than one category header image defined, the default header image should display, and not one of the category images. The project should be completed within 24 hours of being awarded the project. The work will be done on a test site, and when successful done on a live site.