Office closed before official times without notice

I had a reservation to pick up my car from the Avis Bloemfontein Branch at 18:30. I knew I was going to be late so I called the office at 18:20 however no one answered. I was a little concerned that the office was closed however the call agent with whom I placed the reservation with said that the office closes at 20:00. I arrived at the office at 18:38 and the office was closed?! The operating hours on the office door says that it should be open from 8am - 8pm?!? I called the after hours number and was connected to an employee who said that the office closes early as the last SAX flight was at 4pm and it was unsafe for him to man the kiosk alone? I understand that I was late however I was calling since 18:20 to inform them that I would be late and no one answered the phone? I received NO notification. No email, no SMS, no call. Thanks for nothing Avis.