Something fishy here…TOTAL brake failure is EXTREMELY rare. Todays cars have a dual braking system, the master cylinder split into two separate chambers which provide independent braking to front and rear brakes. For BOTH cylinders to fail at the same time is a million to one shot…
The only explanation I can think of is that the rod that connects the brake pedal to the master cylinder somehow broke or fell out of position, rendering the entire system inoperable. Checking the brake-pedal-to-master-cylinder-rod is not part of any service inspection and failure here is also extremely rare…
When your car is repaired, you should ask to see (and keep) the failed parts. They belong to you…