Cheers Mate
I spoke to MotorSportWheels in Bristol (got their number from the BBS website), they told me that BBS will not supply the bolts as maintenance etc must only be carried out by trained profesionals (BBS employees) and if I want to replace the bolt I would have to send the wheel back to BBS in Germany.
I have emailed BBS directly to see if they will take pity on me but to be honest, I don't really expect them to reply.