On my frontend with the booking frontend when the user has to make a booking I get the feedback that the users overlook that they have to select a specific service in the dropdown list --> the default (when there are several services defined) is "-" (dash) --> but perhaps it could be possible to have a "label" setting for this also that you could define the default "-" instead as e.g. "Choose Service" --> this would make it more obvious that this field has to been specified from the dropdown. Perhaps similar label settings could be made for location and worker also????