Bill, a Whistleblower reader in Minneapolis, wanted to alert customers about something he learned about car repairs – the hours of labor noted on the bill don't always correspond to the actual time it took to fix a problem.

He clocked a recent repair at 55 minutes, but was charged for two hours. That's the result of the "book rate," which the shop explained was based on an average time needed to complete the repair - a replacement of his wheel hub. A more experienced mechanic had done the work, enabling it to be finished in less time.

Bill sums up his feelings succinctly, and with capital letters: "WHAT A CROCK!" "I did aggressively pursue this action with the management and did get a $100 credit for work to be done on my car in the future."

The "book rate" or "flat rate" billing system has been around for years. In fact, there are actual books that mechanics use to determine those charges. In one respect, they protect a customer if the mechanic struggles for hours with a common repair.

Did you know that auto repair shops operated this way? Should they do more to explain how their billing works?