E53 over filled oil

[eatswell]

Hi had my 2003 4.6 serviced in early december and since then the power delivery at higher revs feels like it's fuel starved ,did a bit of digging around and think it may be something to do with the vanos system . I may be wrong but is the vanos reliant on oil pressure for its function ? Also would overfilling the oil (well above the top of the plastic indicator) have any serious problems for the engine. I am thinking that this may all be related to the over filling but would like to know before i go to the dealersfor armed if they have cocked up the engine from over filling the oil. Any help greatly appreciated .