I changed mine before the 4 years (just cos it was going into the garage for a service anyway), the indy said the cambelt was in perfect condition and no way needed changing, but of course we did it anyway (I insisted) ,....just in case it went and the worst happend.
Its all total scaremongering and when I tried to get the definitive position out of VW, indies, main stealers they all came back with several answers.