Rob, this is incorrect, if it takes them longer, they add a miscellaneous service code to the repair order and explain the reason why it took them longer (i.e. bolt difficult to remove due to rust..etc) and they charge for the extra labor.Bike dealership use "by the book" times, in order to figure their total charges. If the book says that it's a 2 hour job then they charge 2 hours, even if it took one. On the flipside they'll also charge two hours if it took 3.
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But you are right to say that if it took them 15 min and the book says 1 hr, the customer gets charged the hour.