Hi Nick,
I was talking to a guy the other day about his M% and he had Brembo brake set up on his car.
He spoke very highly of them saying that his stock brakes also felt a little spongy - hence the upgrade.
This is the UK Brembo agent - perhaps they can give you a quote.
Ian
PS - Sorry to hear about your rim - seems like we all suffer the same lack of respect and honesty from garages. I think we all need to digitally photograph our cars, get the mechanic to sign off on them before they start job so we have some recourse afterwards if things get damaged. Sounds extreme, but I have heard too many cases of damage being swept under the carpet and the poor owner left to pick up the peices (and bill)