I have just bought a A6 Avant c8 which has the double screen with the lower one for the A/c and the top one for the mmi system. I went out today and everything was working perfectly then suddenly screens froze then went black. I am not able to see any of the controls but have noticed i can turn on the heated seats etc without being able to see anything. I have message that nothing is working due to the mmi switched off. Any ideas how this can be fixed?