I charge consulting rates, and if you'd ask me to specify by the hour what I do I'd tell you to stuff it. People routinely asking for hourly breakdowns, for work that priced entirely reasonable and who are kept in the loop on what is done and at what rate, are pathological customers you don't want in the first place.

(lawyers are used to billing in 6 minute increments, and while I think it's interesting to go over their bills, I'd pay them (at least my current firm) the amounts they ask too if they wouldn't provide me with a specified bill. I sometimes feel sorry for them, what kind of life is that, having to write down the time for every 2 minute email you write?)

If you don't trust your professional services suppliers enough to pay their bills without knowing what they did hour-by-hour, you need to find other people who work for you, because that's not a healthy relationship you have.