GP Supercharger/LSD probs

[death2pixies]

HI

Just wondered if anyone has had any problems with their GP Supoercharger pulley belt/wheels at all or LSD? Had my GP in for service week before last and mentioned a horrid rattle noise that I really didn't think the car should be making... garage told me it was the diff fluid and they changed..should bed in after 20 miles... 800 miles later and its worse, loads worse. A mate stuck his head inside and said to get them to look at the pulley .. call today from garage saying they are changing the belt and also going to check the wheels out when they take everything out to change the belt.

I've only done 30k miles, never had similar issue before on either of my S's but this is a JCW kit so is this normal? Should I be having these problems with relatively low mileage? Also have they just taken my mates word for whats wrong... ?

thanks :-)