This car has a really complicated central hydraulic suspension system. I have worked on them and they are really complex and the parts are very expensive. You need a Mercedes capable scanner to first track down which part of the suspension system has the problem, then you need to replace part(s). I would go to a good German shop, as central suspension needs a lot of attention on these cars.
ABC and air-mattic suspension problems, like the one you are experiencing, are common. There are many different causes for these problems. The problem could be caused by anything from a bad shock, leaking line, valve distribution block malfunction, ect.. I recommend having a professional diagnose and repair your issue. In addition, if the suspension does not come up, with the vehicle running, you should have it towed to prevent any further damage.
very common problem on S55's after 80k miles, the valve part can only be purchased from MBZ the cost is $1300, labor to install is $1100, total cost is $2400, a guarantted replacement issue if you have a S55......generally the right/passenger side fails, very unusual for the left valve to fail from wear