Bookings - multiple sudden glitches - booking notification and staff assignments

Not only has there been no solution, or evidence that this has even been worked we now have additional glitches.

- booking in Universal Coordinated Time - it is clearly set not to do this

- also bookings at times clearly not available either as normal business hours or for the staff member, and seemingly not available on the booking form either. Client has a booking at 11.30pm which they didn't select (and isn't available) and they weren't using a different time zone on their end either....

edited to update another time/date related:
- Setting Time off for entire services and staff over a full day is not working, still allowing bookings on days that should not be available at all. Not related to (UTC) Coordinated Universal Time (at least in theory) as the times do not match up with the 10+ hours availability that all the other UTC issues have. 

- Have tried resetting regional time zones, Outlook time zones, deleting and re-adding Time off (actually made it worse). We don't use the "Events on Office account affect availability" because we use a dedicated shared "staff" email.