+1 on checking the mute button......
If that is/was the problem your dealer should be given a serious ass kicking
With the avc on, my volume is set to no more than 16 running 65-70mph.
If your dealer pushes what he thinks is the mute button and the horn blows....run as fast as you can to another Honda dealer
Please update us on what the problem was.
Good luck!
Ride safe,
G