WORST EVER!!!! Pensioners got a bad deal!

My parents rented a car through thrifty after a previous not so bad experience by myself. They rented the car for R3000 and had a R6000 holding fee and are still waiting for money back after 12 days and counting. My parents are pensioners and are now left with almost no money for the rest of the month. You people are *****s!!!! What can I do to get their money back? Please nobody use them ever!!!!! Flippen ******. I actually want to swear and make their name so bad that nobody will ever use them again and that the company will fold. GIVE OUR MONEY BACK YOU IDIOTS!!!!