VW Golf 'Infotainment System' - HELP!

[ak67]

I have a 65 plate VW Passat R line and have just encountered an issue with the infotainment system. I have seen lots of posts about the screen going blank but I have a different issue. It happened last Friday when i got in the car and pressed the start button. The infotainment system came on with the radio as usual but it was at full volume. I couldn't adjust the volume at all and after 8-10 seconds the system went off and then came back on 5-6 seconds later, again at full volume and then off after another 8-10 seconds. I got out of the car and locked/unlocked and started again but exactly the same issue. When the system comes on I can select the different functions on the side buttons and have touch screen control but the system always shuts off in the same time scale. I have tried holding the power button on to try and reboot but this doesn't change the issue. I have contacted my local VW garage who couldn't offer any advise over the phone and they apparently can't book me in for 40 days!! Plan is to try another localish dealership to see if I can get some info but if anyone has any alternative suggestions or is aware of this problem then please let me know.