Non existent customer service.

I regularly use Dollar Thrifty, and as I write this I am starting to wonder why! On more than half my recent rentals I end up having deductions made from my credit card for refuelling, despite invariably refuelling the vehicle immediately before return. When I try to contact customer services by email I get no response at all. Additionally, trying to get an invoice from Thrifty is like trying to get blood from a stone. Surely this should be part of the rental package? Very disappointed. The only bright note is that front desk staff at my main rental location (Durban Airport) are very good and efficient. Wish I could say the same for their so called 'Customer Services'....