well I priced a base up.quick call to bmw found out a new base was £240 odd quids plus vat so I carefully drilled into the snapped off thread on my base with a 4mm drill then ran a 5.0-8 tap into it and bingo fixed took all of ten mins
Pretty sure someone said the bases where like £10, I wouldn't have put it past BMW to have quoted you for a completely different part :| Not to worry, sorted it yaself!