I have a 2004 mercedes e class wagon. i am second owner. since i had it in 2007 the panel showed a car with an arrow pointing upward. the message recommended maintenance. none, even mercedes mechjanics could figure out the isue. now in 20112 i know what it is. the car sinks low in th e rear. the message on panel tells me to stop car too low. i tookit to a foreign car expert. they tell me air bags in rear lift the car. they said ithe bags leak. the cost would be 1200.00 per side. I cant afford now so i just start and restart the car till it wakes up and lifts. does anyone have an opinion on whether thias is the correct diagnosis.