Should I have to pay for my spark plugs to be replaced?

My engine misfired in my first cylinder. It was diagnosed that my ignition coil and spark plug caused my computer to short. My mechanic ran a diagnostic. I have a 2007 Ford Fusion. I did some research and discovered that it is very common for computers to short due to a bad ignition coil and spark plug. I authorized him to replace the computer. I asked him specifically do my spark plugs and ignition coils need to be replaced. I was told no by my mechanic. He also replaced some other things that included a motor mount, rotors and brakes. On Friday I was told my car is fine and back to running properly. Literally three days later my car is shaking when I drive, brake and in park very bad. I take it back and I'm told I need new spark plugs and ignition coils. I refuse to pay for this work when I was told I don't need literally on Friday afternoon I didn't need the,

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