Invoice not received after 5days

I rented a vehicle from Europcar Cape Town International Airport from 3 - 10 October 2015. The vehicle was returned on Saturday 10 Oct 2015 at 12h00. I was informed that it takes 3 working days for the invoice and the refund on the deposit to be processed. A week later I still have not received my invoice or refund. I called customer service 4 times in the last 2 days and sent an email. No response as yet. They keep telling me that they will forward the request to the billing department, but nothing happens.<br> <br>