Big O Tires review: Erroneously charged "diagnostic fee" which I did not approve

On June 21, 2023 I went to Big O Tires, Bozeman, to have them check out a noise under my vehicle's hood. After fifteen minutes, their conclusion was the power steering fluid was low and they filled it. For this fifteen minutes, I was charged a "diagnostic fee" of $145. In fifty years of dealing with auto mechanics, I have never encountered a "diagnostic fee." Contrarily, I have always experienced the industry standard with is the mechanic looks at the vehicle gratis, then provides a written statement of what needs to be done and the expected fee. Law requires this to be done, and to have a covert "diagnostic fee" as the means by which to obtain money from unsuspecting customers is disregard to the professional, legal requirements of the automotive repair industry. Big O Tires website states "Big O Tires has provided straight answers and reliable service you can trust since 1962. We do this because you're our friends and neighbors, and we feel all our friends and neighbors deserve a legendary service that they can trust." I approached the Big O Tires Shop Manager for a straight answer, which he refused to give me, asking rather about my personal life, which was unprofessionally relevant.