https://youtu.be/o81GjHj4z4s Don’t know if the link works, but check out stripdip. Pretty good video explanation of copper in brake lines. Brake fluid absorbs moisture and degrades, gives you a soft pedal and moisture in system causes corrosion. When was the last time your brake fluid was flushed? Sounds like a professional operation to me. Maybe shop didn’t explain properly or customer didn’t understand? Just because the shop was recommending a service doesn’t mean they were trying to rob you. Call any properly trained professional. plumber, electrian,doctor etc to diagnose a problem.. time is money
