Hi, I have a 2007 C5 VTX+ Estate (1.6 HDi). I have recently noticed that it sits down almost onto its dump stops when left for a few hours (typically overnight) As soon as the car is unlocked the pump can be heard and it lifts back to normal. Driving is uneffected and everythign else seems normal - although I have noticed that it seems to raise and lower for no apparent reason when it is parked up with the engine running. It raised and lowers for anything up to several minutes. Any help or suggestions? Thanks