I am writing to formally express my extreme dissatisfaction with the way my recent warranty claim was handled

I am writing to formally express my extreme dissatisfaction with the way my recent warranty claim was handled. The lack of professionalism and disregard for my concerns have left me frustrated and disappointed. Firstly they rejected my claim as me claiming for something that’s not in my car, ,proved them wrong then changed their tune that its wear and tear,even though the part fail way before it was due, ,now excuses that they had a recording of my conversation with the mechanic but can’t produce. The back and forth was totally unnecessary