Nissan dealer charges parts I will not use

I took my Nissan SUV to VOB Nissan on Old Georgetown Rd in Rockville to have them look at a problem with the airbag system. They looked at it, charged me for the diagnostics, which was fine. But then they gave me an inflated estimate of how much it will cost to fix the problem. When I found that another Nissan dealer is willing to give me a better price for the work I cancelled my order with VOB. VOB then charged me an additional $143 for ordering the parts, parts that will not be used in my car. I told them to cancel the order but they refused, saying that they can't cancel any orders. I find that hard to believe in this day of internet and instant-messaging cancelling an order is so difficult. They blame it on the Nissan corporate parts system, telling me they are powerless to change this type of unfair practice. On top of all this the Service Manager was rude and condescending, telling me I need to be educated. Consumers should beware of this dealer.