My car is great, it does all that I want it to do and I am very happy with it but I am a little concerned about the gear change. Sometimes, and it it is only sometimes, it tends to stick in one gear and if I continue to drive it whips into another gear very quickly so much that there is a jolt. This car has just been in for a full "non Mercedes dealer" service with no problems found, they tell me that the gear box has to be serviced by a Mercedes dealer. Can anyone tell me what this jolt that I have experienced is all about before I have to take the plunge and take it to a Mercedes dealer? I will be so grateful for your comments.