Hi Jim , excuse me for poking my nose in here but I do all my own brake work including new system lines and hoses. I don NOT however have any experience with a ABS system YET but obviously will one day because of the LSS, which is still fine.
Anyhow, I beleive you are now a victom. Its been said that ABS is a bit__ to bleed once run low, which surely happened to you because thats what happens when a line blows. I have done numberous new system under my old cars. Some have masters that are now 29ys old. NO PROBLEM WITH MASTER after bleeding.
You have a virgin by todays standard master cylinder. I seriously doubt you blew both a line and the master at the same time. In fact the master was working great to blow the line. Dealership shops and I hate to say it but its true and true with most shops make big bucks on "suggested retail" parts prices and "hey the guy dont know anything about his car so ?" "you need this and this and this".
Back in 90 my father gave us his 82 VW diesel (no trade in value) with 150,000 miles on it. Every year they took it to VW for a "check up" and sure enough, it needed this and this and this. In with the owners manual was a stack of repairs I never seen in my life. many CV joints, many wheel bearings, many other outragous stuff. We drove it for another 110,000 miles and never needed a CV joint or bearing. Only a front engine mount and an alt. I mean it didnt need anything not that I just let stuff go. All the miles we've put on cars I have very few repairs that needed to be done and all that were, were rust or highmilage ware items. People that go to "tecs" artists formerly know as "mechanics" have repair upon repair upon repair.
Theres big money in a dealership shop and they run it like big business. If a survey was done at dealership to determine a models reliability after original owner they would all fail the reliabilty test wickedly. A dealership is like a tourist trap !
Why did they send you home with soft pedal ?
You get this fixed, then I guarentee you have another serious problem within 6 months to a year with another critical function in the car, that is going to require dealership only repair or atleast parts. Why did your Bonneville need so much in repair ?
I do my own work for a reason, and your finding out right now.
BTW I do hope I am wrong and you do really have a bad master and they dont toy with other functions of the car. I have never need a master and all my cars have been old and high milage.
I'd go tell them to bleed the air out and "I wanna see nothing but fluid comming out ot the lines".
Good luck I do hope for you that I am wrong.