[zamler]

I find some parts of this issue to be dubious. Firstly, unless the brake fluid level was dangerously low, you would only be able to add so much oil before it would overflow the reservoir. Secondly, there is no reason that motor or transmission oil would destroy the rubber in such a short time, brake components use rubber that are highly resistant to just about anything, I doubt a short time in contact with say motor oil would do significant damage. And the price is way out there, a brake system contains for example 4 calipers and a master cylinder, plus the ABS unit. Replacing all the calipers and master unit plus flushing should not be anywhere near 3-4 grand.

And yes need more info, make and model of car. I would take it to another shop, or PM me if you like I'll be happy to look at it for you if you don't mind coming to my place, I'll do it for free (BTW, long term motor oil exposure in the brake system WILL swell the rubber parts).

edit - reading your post again, it sounds like the oil could have been in the system for several months, that is enough time to damage the rubber pieces.