iPhone 4S cannot connect with USB to MMI
 

Hi
We have an Audi A4 Avant
It's a good car, but the Multimedia system drives me crazy - it's stuck somewhere in 19 century, but that's not the main point. The main point is, that neither my iPhone 4s, neither my wifes iPhone 6, both with iOS 8 cannot connect to the multimedia center through the installed USB connection. I also cannot set it as source through bluetooth, though I'm not sure it was meant to be possible. Actually, the only thing that I can connect to the USB is a USB flash drive with some track, and that's all. This is ridiculous to spend so much money on such worthless peace of equipment... Does somebody experience the same problem?
Our Audi dealer said, that iPhone 4s should work, but they are not sure, and that for iPhone 6 they will issue an update probably soon. really - how difficult it should be to play music in a car?!?