Best Buy Service Plan for KP53HS20?  

I bought a SONY KP53HS20 from Best Buy a few weeks ago. I ordinarily never buy special maintence contracts etc., but was convinced to buy the Best Buy one because I could also get the settings tweaked whenever I needed. It is not too late for me to cancel and I'm guessing I should have said no. Advice appreciated! Could I do the tweaking myself, with the service manual and a careful approach? TIA, Chuck Sherman