over reving Megane II

I own a megane II 1.6 sports car, but ever since I got the car, when ever I change gear, the car over revs. it is paticularlly bad in first gear. I have been to renault serveral times but to no avail, has anyone else come across this problem?

Its a pretty common problem with the megane. First gear is practically non-existant and second ain't much better. The only feasible solutions would be:
upgrade the ECU (expensive)
Install high lift cams (expensive)

:eek7: how can that happen?