Exhausted Amount demanded to retrieve belongings

I took an uber trip which costed R20.00.

After 45min, I realized I left my keys in the UBER. Upon calling the driver, I arranged a time and place which was convenient for him and also advised that I will compensate him for my time.

When he arrived, he DEMANDED that I give him a R100 or else he will be leaving with my keys.

Firstly, whether he is a partner driver or not, that has nothing to do with me as a rider. As a rider, I use the UBER platform. UBER support blatantly told me there is nothing they will do regarding this. So UBER allows drivers to do this to their RIDERS??? This is unacceptable. I wouldn't have mind compensating the driver for his time as I told him but for him to demand such a high amount and threatening to drive away with my keys?

For everyday that I do not receive a response and a resolution that is fair to me as a rider, I will be using every social platform I can find to express my experience about this.