Automatic Transmission problems of the 1998 Infiniti QX4

My infinity 1998 Qx4 has about 88000 miles I bought a demo in Jan "99 recently I had to replace the transmission at a cost of $3000. 00. I took it to a Nissan dealer but they said they could not waranty it because it was an infinity so I took it to an aamco. Who waranteed it for I year. I must have changed the brakepads 3 times and accept for the drivers seatbelt none of the seatbelts work, also during the first year the tires had to be replaced,I contacted infinity and learned that tires that come with new vehicles were not waranteed. This is my 4th or 5th Nissan product but never again!.