It has been mentioned that my problem could be the mdf,and not the box. Looking at past records i see that under warranty when it had done only 6k miles and three year old it had  a new dsg flywheel, is that a mdf ?.We have done 59k since new, 55 plate.

Its a DMF not mdf (MDF = medium density fibreboard). A DMF is a Dual Mass Flywheel.