general problems of the 2002 Mercedes Benz Cl Class

Left rear of car sinks after sitting for more than 8 hours. Mercedes benz has repaired many times but the problem still comes back. Repaired measures include replacing valves associated with the abc suspension, the abc pump has also been replaced and have also flushed the abc fluid and replaced the filter on many occasions. However, the problem has not gone away. Sometimes when the car is sitting for more than a day the active body control alarm comes on in the instrument cluster. I have not observed any abc fluid loss.