Fraid so, every six years, part of Lamp is it is required to be done IAW the manufactures limits, you could try writing to the CAA asking for an extension., though whether you will get one is a different matter. Other possibility is your engineer may be able to write into the servicing schedule for the aircraft a different limit, but you or he will have to justify why he is not using the manufacturers limits.
As for FAA
http://www.caa.cz/file/1974_1_1/download
For what it's worth, several years ago I had a brand new Mcauley prop start to delaminate due to inter granular corrosion and it was under 2 months old and had done about 30 hours, it was Bly visible due to paint erosion and was replaced under warranty.