Bad service - bookings might be easy, but service is not

I collected a rental vehicle at Lanseria Airport on the 5/3/2020 for a 8 day rental period. On my way to Pretoria, I discovered that the air conditioner was faulty in that it only works if it is set to the highest speed. I sent an email to customer services and have up to date not had any response. It has been 5 days with absolutely no action from Dollar Thrifty. Disgusted with their customer service and disrepect.