"drill and tap out" bolt holding battery in place

While I am not faulting the actual work done on my car, I seriously fault Conway and O'Malley on the fairness of their prices. Grossly overcharged for the, I hesitate to say work, done on my car. The bolt rusted out which holds the battery tight in place. It is easily accessible once you pop the hood and shouldn't have taken more than 10-15 minutes max to fix. The mechanic and the service people at the front told me to my face that it took half an hour to "drill and tap out" the screw and replace it with a new one and so I was charged $39 for the fix. When I said that I doubted it would take that long, the man replied, "Well I can fail your car and you can get it fixed someplace else." With poor customer service and I feel, outrageous prices, I will be looking for a new place to take my car and will mention to others to go someplace else. Just because I am unable to do the work myself does not mean I am a moron.