Hi,
Seems that a theme style is involved in the time picker area, however this style should help (add it to the “Edit Styles” area of the plugin):
.slotsCalendarfieldname1_1 { width: 95% !important; }
Note: The above is valid if the calendar field ID is “fieldname1”. If it has other ID (can be checked in the form builder) then replace “fieldname1” with the related ID.
For a more exact solution and information about the style affecting that time picker area I’ll need to check the page. To indicate the page that contains the booking form you can post a private ticket at https://wptimeslot.dwbooster.com/contact-us
Thank you for using the plugin!