Where is my invoice??

Rented a car from AVIS in Cape Town 25 - 27 October. On Monday 02 November I sent them an E-mail asking for my invoice. No reply. I sent a second E-mail yesterday and still no reply. I call \customer services"and explain my request to them. Was promised the invoice would be sent right away. STILL NO INVOICE. Sent a THIRD e-mail AND STILL NOTHING!<br> <br> WHAT MUST I DO TO GET MY ****** INVOICE? Why do I have to waste so much of my time on this??<br> """