First car rental - car broke down and call center useless

The car refused to start on the third day I had it, without having left any lights on or unlocked. The unhelpful car center told me I can lay a complaint on their website, yet I was left in danger with no assistance at 10pm in the evening. They also have the audacity to take a 7500 rand deposit - higher than other rental places even when I paid upfront for the car hire.