Poor customer service

I am really disappointed with your customer service staff. I hired a car and when I returned the car I was 14 minutes late, I was told I am not going to be charged since I am only 14 minutes late. by the time I left your premises I was charged over R400 for being 14 minutes late. Everytime I call to enquire about this, because I was told I am not going to be charged unlesss I was late by over 30 miinutes which I understand. Your customer service promise to come back to me but they never update me as to whether I will be refunded or not.