Rounded the flare nut bolt for the brake line, what to do next?

[chi123]

Was installing stainless steel brake lines and rounded one of the four flare nuts. Had a set of flare nut wrenches but they skipped the 11mm size. So I used a regular wrench and 3 of them broke loose easily but the rear driver side was on tight. Thought I broke it loose but it just got rounded. Went to the store to get an 11mm flare nut wrench but it slips. Tried using PB blaster and that didn't work. Lastly, tried using vise grips but even that can't break the nut loose. What's the best thing to do next? Does Audi sell the hard lines?

[AudiTechS4]

leave that one alone :) is the best thing to do

[Sceanzo]

Vice grips. Preferably needle nose. It'll look like shit before and after but it will do the trick

[infinkc]

Vice grips. Preferably needle nose. It'll look like shit before and after but it will do the trick

Yup, vice grips

[skinnytirez]

Use vise grips to get it loose and then go to autozone and buy a new nut, and rent a brake line cutter and flare kit.
Cut 3mm off slide the damaged nut off, then slide the new one on and crimp in a new flare. Bingo good as new for a couple bucks.
https://www.amazon.com/OTC-6502-Mast.../dp/B0075XHDHI

...or go to the dealer and buy a new hard line. Bend over and prelube if you go this route