Unexpected expense from bi-annual brake fluid change

[outnumbered]

My local BMW dealer managed to shear off the bleed nipple on one of the front brake calipers, for which their solution is to replace the caliper at my expense

They're claiming that sometimes they just shear off due to corrosion and there's nothing they could do, and it's a safety issue to try to extract the remains of the nipple as they might damage the thread and it'd leak in future. After I complained to the service manager they've agreed to reduce the replacement to @cost or thereabouts, but it's still going to be a significant outlay.

I thought about getting the car to the good local indy to have a go at drilling the remains of the nipple out, but since I still want to get a BMW stamp for the warranty, it'd then have to go back to BMW anyway, and I can't be bothered with the hassle as I'm going away at the w/e.

Can't wait to see some more official documentation from Mondial about using non-franchised dealers for servicing, so I can just take the car to somewhere I trust a lot more...