Len The Plummer review: Excessive charge for faucet repair

Recently there was a running leak from my bathroom faucet. It started as a drip but over two days progressed to a thin line of running water. My plumping warranty did not cover the faucet, so I called Len. Apparently, the problem was a corroded "shower cartridge". The plumber replaced the cartridge but broke a knob that turned the water on and off. He charged $89 to get a new regulator and approximated $780 for the repair. I believe I was overcharged for approximately 30 minutes of labor and materials. A manager has not responded to my call for an adjustment of the charges.