Tempest Car Hire deduct money without authorisation.

I rented a car from Tempest at OR Tambo (via the Holiday Autos agency). I paid the full rental amount plus deposit. However, today another amount of around R2200.00 has been debited from my credit card. This is an unauthorised deduction, which is highly irregular. Also, when I wanted to visit the branch of Tempest in Randfontein, the building was closed. Don't they update their details on the Internet either. This will mean that I have to visit a Tempest branch to sort this out, involving petrol costs and time wasted. Please investigate this matter urgently as this is unacceptable.