Electronics nightmare

I would like to know the method used to determine that my claim no 3 under this policy was declined due to normal wear and tear. Hence, if it were that easy to tell the difference between the power surge and components failure in the circuitry all of the technician would have been accurate as to what is the exact lifespan of the capacitor; diode; etc? As far as it is you have failed me, cause every time I claim for any appliance I will be met with this lame excuse. Yes mechanical it's much easier to tell if the component has failed. Not having some backyard technician to have it opened and say the electronics have reached their lifespan