Unsafe Car Provided

I hired a polo TSI from Thrifty Sandton which turned out to have faulty brakes (the car would vibrate violently when applying brakes). I only found out whilst on my way to White River. I then called into Thrifty, got put through to some mechanic who was of no assistance just saying I should go to a filling station and spray air on the brakes as there is dust causing the vibrations, was not willing to call me back to determine if all was still ok or not. I had to find my way around Nelspruit looking for another Thrifty branch to change the car. Got to the Nelspruit branch, being assisted in calling the Sandton branch which again did not yield any results. My disappointment in the service provided by the Sandton branch especially after I described the car being unsafe (the least they could have done was deliver a car to me and not ask me to drive an unsafe car trying to locate a branch for an exchange).