Phaeton junk?

Hello. I would like to turn briefly to the phaeton experts. Unfortunately, I don’t know at all. I still have a Phaeton 5.0 TDI long built in 2005. The TÜV IST 11/2013 expired. For 3 months he stood in the garage. Before that I moved him sporadically. When I drove out of the garage it squeaked and there was a liquid in the front left side. I gave him to a friend. There was a tube rusty/porous or similar from the servo steering front. With an exchange 700€, away. When I wanted to hire him now at mobile he drove only with about 90 hp when driving back to the garage. We had to refill about 3 liters of cool liquid after 10 km. The rear left footroom is totally wet/humid. Apparently there has to be a leak. So after the whole bla bla bla my question. What do the experts advise me to do? I pay 160€ to 12/2015. then the residual value of the VW bank is set at 6069€. He now has 180.000 kms worth of repairs etc. I would like to buy some good advice. I can’t.