Hi Kiska.
I'm guessing you've solved the fading radio volume and beeping sound by now. I have just bought an i30 elite (2014) and had the exact same problem.
And for those that come after me, this is how you fix it.
The fade and beep is related to the "PROXIMITY ALERT" in the navigation system and unless you like the radio fading and the accompanying beep you just gotta turn this feature off!
If you don't know already, this how you do it:-
1. Press the NAV button (RHS of screen)
2. Press the "+MORE" icon (Bottom right of screen)
3. Press the "Settings" icon (top left of screen)
4. Press the "Sound and Warnings" icon (top of screen)
....you should notice that the "Proximity Alerts" icon (bottom of screen) has a yellow tick in the box on the right.
5. Press the "Proximity Alerts" icon.
....the yellow tick will disappear and so will the annoying radio fade and beep.
Hope that helps