How can you replace the fuel pressure regulator on a 1997 Pontiac Firebird?

I just had the fuel pump changed at a cost of $1350. Then the fuel guage was faulty so they had to take the whole system out again and send it back to the manufacturer and no cost to me. Every time I take my 1997 Pontiac Firebird Formular in for any service they say mine is the most difficult car on the market to fix. Tomorrow I need to get the spark plugs changed and they say that will need to include a full tune up at another ridiculous cost $600 because mine are the most difficulty to change of any car. Do you think I am being ripped off by my garage? I bought the car new with 42 miles on the clock and now it has 100,000 so the electrics need checking. I have done everything the log book said with dates on each service. I love my car but the costs are getting out of control because - "This is the most difficult car on the road to fix" - according to mechanics. hmmmmmmmmmm!