How do I fix incorrect appointment time and telephone number on iPhone and Macbook Calendar?

My calendar on iPhone and Macbook all the sudden changed the time zone without my doing anything. And I manually added my PT appointment, added the address by typing the name of business in the address line. It found the correct business and address. SAVED.

But my 8am appointment came out as 6am no matter what. And somehow it added the telephone number of my old PT with completely different name (10+ years ago) 2000 miles away. So the telephone number of the business and the time zone that came out automatically match.

I checked the calendar and system time zone - they were correct. I checked the Macbook, the same problem.

The calendar app on Macbook has the alert - "your calendar could not be refreshed." (see attached), and I could not refresh it manually either.

I just cannot correct the appointment time to the correct 8am for this one. All the other appointments seem to be correct.

[Re-Titled by Moderator]

Original Title: Telephone number of a business on the Calendar automatically inserted - that is 2000 miles away.