I have a audi a6 2.7 tdi s line quattro 56 plate

The MMI is playing up, I was listening to radio at lunch time having a snooze with the key just in the ignition. After 10 or 15 min it went off. I thought nothing of it. turned it back on & the radio start going out every few seconds. now the cd player isn't working the sat nav isnt working the phone isnt connected to the car?
Any help would be apprieciated, Audi want £150 just to look at it

thanks
Icemen