@Idil7
Welcome to CC,
There have been IT glitches in the systems worldwide which is very frustrating.
If you can contact ABB Customer Services/ Technical Support to report the issue & fix it up.
There's discusions about these issues in CC if you use the search box, key words Calendar Malfunction and Log In IT and similar terms.
Make sure you also provide "feedback" via your listing & to get the Guest to also report it so it's recorded in ABB systems.
All the best
Central To All Home & Location