mmmm try lubricating the drive belt with Silicone lube - it might work - and if not no harm done!
Failing that it could be the dreaded bevel drive - which version have u got ? The factory would be able to tell u.
The car is only 8 weeks old so has the latest bevel box. The bevel box is actually very quiet,the problem lies within the compensator assembly (cush drive) this is what is being replaced.