Not understanding reason is costing you money Thrifty

Returning my rental car 25min late due to the rain storm that was in Cape Town on the 14th of June that caused floods and i had to stop on my way back from Herm**** to Cape Town due to the amount of rain falling down and lack of visibility and not to damage the car in a accident, The manager at Cape Town airport did not see it fit to understand the reason of being late. So they charged me a extra day fee. Even speaking to the manager in Johannesburg but nobody understood reason. So just wanted to let them know thhat i have managed to stop our company account with them and also 4 other people that use Thrifty all the time. So how is that for making an extra R550 for the day but loosing out on a few thousand rand a month going forward?