overcharge for auto repair services

I took my Toyota Sienna minivan in for an oil change, alignment, diagnosis of "check engine" light. The oil change was fine, but they charged me $110 for the "check engine" diagnosis. When I told the service tech that seemed like a lot just to plug in the tester (AutoZone will do it for free), he said he assumed I already knew the fee (why would I know that??). When I suggested to Mike (manager) that maybe they should tell customers in advance how much that service would cost, he basically tried to argue with me (in a polite manner), so I just paid and left. The car still pulls to the left, so I don't know what's up with the alignment. Also, when I took the car in for tires last November, they told me it needed a new tie rod; this time they told me it didn't need it. When I pointed this out, they had no explanation. They were all polite and called when they said they would, etc., but the overall service was not good and I won't be going back.