My Phaeton is crazy….

Hello everyone, my new (older, EZ 12/2007) Phaeton is ticking tremendously….Shortly to the course… Purchased with defective tailgate……Car had stood a little longer….ZV didn’t go, car was sold in commission, therefore actually sold privately. I gave the order to look up the batteries, if they were too old please exchange and possibly charge, statement of the workshop: battery is from 2014, everything is good, I looked, can not recognize the age of the comfort battery. On the Fah I wanted to lock the car manually, went, after about 3 minutes the alarm went off, I had my trouble to get the beep out again. Shortly afterwards, about 2 km, the engine control light went on, car drives only 60 km/h. Oh menno….Woman panicked…..they must have betupt me..:-(( Arrived at home, man mots….Comfort battery measured, man says battery almost dead, woman why do you buy only such a scrap…. .Yes, yes, I know laughter…. No seriously, is my Phaeton still to be saved? I can imagine that I need a new battery, but the engine control lights worry me, she says: Woman drive in workshop….I hope you can help me….. Greeting Benitolino