Brake Light On problems of the 2015 Volkswagen GTI

After driving home from the gas station after replacing my tires going about 50mph. My brake fluid light came on and the brakes did not work at all. Lucky I was able to down shift and e brake on the city street. I took it to the firestone mechanic. Thinking the hit a line or cut a line on accident. After inspection nothing was cut or broken. After opening the hood it reviled no brake fluid at all. After removing parts it was then discovered that the master cylinder was leaking in the firewall. After going online to the forums I noticed other people are having this problem. The dealership for Volkswagen are trying to blame them. . But they didn't even open the hood. I had other work done by them with no problems ever. I will have documentation as my car is being worked on. I could of died if I didn't think fast or if I waited till the last min to brake.