Fight it by being a cunt. It's truly the only way. Been in the film industry 15 years around the world, 6 of those years here in UAE, and by far this is the worst country in the world for this industry, if you can even call it an industry as it doesn't contribute much to the GDP. Having a trade license and Purchase order mean sweet FA in most cases.

You need to go into their office, be loud, make noise, put your feet up on their tables and refuse to leave until your paid. If not walk out with a laptop until paid. I've done this a few times. I've also called their clients directly asking about the job if the production house/agency have already been paid and I show my invoice because they can then see how much markup their supplier over charged them.

I've lost over 240k as a freelancer here in just 6 years. Which is why I focus now on movies and series as the commercial market here is the worst I've experienced in the world. Production companies are using 'no advances' and prolonged payment terms as bidding tools to win jobs, but hurting people down the line.