Worst service received from Dollar Thrifty Car Rental at Cape Town International Airport

I am receiving the worst service ever with Dollar Thrifty Car Rentals at Cape Town International Airport. I hired a vehicle in September and up until today they have not released my deposit.

I have been calling and sending emails. All I get is promises and still nothing. Their service is unacceptable and I would not recommend them to any of my friends, family and colleagues.