STAY AWAY! An aftermarket warranty covered repair will turn into $3000 damage!

Midway through a transmission rebuild, the owner called me up and told me that I need a new clutch. I went down there and he showed me "a clutch" that is worn down to the rivet, I have no idea if it was mine. He phrased it as "physically impossible" to put the clutch back in! He broke the safety mechanisms that lock me out of gears (locks me out of first gear if I go over 30km/h) in the process.
The car started to shift hard after 2,000km and impossible to shift after 5,000km. I couldn't bring the car back because I was on a road trip to California. By the time I got back, the car has gone over the mileage of the warranty he gave me. I was told that I have three pieces of broken clutch in the car by another shop when I replaced the clutch again! The worn clutch caused the synchronizers for 2nd and 3rd gear to wear and those two gears ground every time I shift too fast. The transmission still makes some weird rattling noise like there's a bag of loose washers in there.