Time is wrong when day starts at half hour

Hi.

I have a problem with the hour intervals.

Whenever I start a day at the full hour. Like 10.00, 11.00, 12.00 or so on, everything works fine. It shows correct time in the booking calendar.

But if I want to start a working day on the half hour. Like 10.30, 11.30, 12.30 and so on, then it moves the time up by one full hour.

Example. The working day starts at 10.30. When we look in the booking calendar it says 11.30. If I change it to 10.00, then it starts at 10.00. This i s a mayor problem for us, since all days start at 10.30.

How can I fix this. Start working is set at 10.30. If you see this link you will see that it shows 11.30.

http://perfectescape.no/lillehammer/the-sub/?wcalendar=1455015558

I have giver you Support Staff Access.