Megane 1.4 Sport Alize (99), Squeak from engine

[clarabug]

Hi,

I have recently bought the Megane and upon purchase it had a irritating squeak coming from the engine after having a good run. I have since taken the car back and they have replaced the cam belt and pully's and have also put 16 new valves in. Unfortunately it is still squeaking and the garage are at a loss on where to go next. Does anyone have any ideas on what it could be? It will more than likely be something simple, which will be good as I have been without my new car for three weeks!! Help will be very much appreciated.