lol. Honda's one solution to the worlds problems, use Hi Octane! Don't bother with that, your car is new and doesn't need any special treatment.
My City 2011 also drops the RPM when I brake with AC on. It only does that when the FAN is on. Have you noticed if it only does that during really hot days and when the car has been driven for a long time (all day maybe). The RPM acts normal if the fan is off. Try noticing that and don't waste your money with any more HONDA visits.