Dear Arthur,
first of all we organize walking tours and day trips, we are not booking hotels, you should address your hotel complaint to someone else.
Then i have to inform you that the tour leader always do explanation during the cruise, this is the most important thing on our experiences, if you couldn't ear that it was only because you were sit too far from the tour leader, that obviously couldn't locate you too.
Next time i suggest you to don't lose your group and sit close to the tour leader. The headsets are different from mobile phones and need shorter distances to work properly.
Best Regards
Davide