Please HELP, MMI gonna make me insane

[Cricket0310]

I have a A4 B8 2009 which im sure has the 3g hdd mmi with sat nav etc. when i bought the car i noticed when reaching destination with sat nav and stopping route guidance it would freeze, shut off then power back on and be fine. Didnt have a problem with this as would hardly ever use sat nav anyway. I advertised my car for sale and behold it started to judder like hell so new clutch and flywheel!! Since this my mmi has stopped working. On start up it takes few minutes to power up then media and radio work fine whilst nav and telephone are initialising but then freezes. I can still turn volume up and down but everything else freezes. It will then power off and come back on after few minutes and continuesly does this. Funny thing is that when i take the key and lock up the mmi stays on. Iv tried the reset no luck, took it to vag specialist he says loads of errors to do with low voltage but battery is fine, he thinks its because the mmi stays on. He did mention that the car is saying it needs software update?????, so went to the dealer today to get emmissions crap update and audi say it doesnt need an update, what the hell is going on, (they gave me an audi cleaning kit for my inconvenience and showed me the door). The buttons dont seem to be sticky, i pulled the fuses in the back and checked fuses on right/left side of dash all seem ok, im so flippin stressed i dont know what or where to go to sort this mess out, sorry for the long post but had to get it all out to hopefully people who know what they are taking about as everyone ive spoke to doesnt have a clue, i keep turning down people who want to look at the car and advertising is costing me an arm and leg!!!!!