The mechanic seems to have installed a CVT K114 transmission on my Alphard AH30 without my knowledge, and it broke down within 2 months.

My Alphard AH30's transmission broke down a while ago, and at that time, there was no K115 transmission available. I searched for a whole week, then continued searching for a month. Eventually, I went to a mechanic who said they had just received a transmission, which they had bought from an auction in Japan. Unfortunately, just two months later, the transmission broke down suddenly. I happened to have a relative who is a mechanic, and after inspecting my car, he said that the mechanic seems to have installed a CVT K114 transmission, along with some parts from my broken K115 transmission. He explained that because the K114 has weaker torque and is designed for smaller cars, it couldn’t handle the load, causing it to break down. He also mentioned that K114 transmissions are abundant, but K115s are very scarce.

However, my mechanic insisted that it was a CVT K115 transmission and that he bought it from a Japanese auction but couldn't provide a receipt. I want to file a police complaint and would like to know how likely it is that the mechanic installed a K114 transmission on my car. Is it even possible?