Any ideas how to bypass immobiliser on Megane Scenic W reg Alize Sport?

any idea if / how to bypass immobiliser as seems to stick more frequently these days, unlock with key fob and insert key into ignition and engines turns over but won't start (seems to happen more when its been raining ) have sunroofs but these do not leak! fed up now, was going to order a new key but after listening to other people this doesn't seem to cure the problem.....