Make changes to a thing issue

My app asks users to input their time slots. In my db, i have to types: User and Calendar:


My goal is to have the fields in the calendar for the user to be updated whenever User makes changes to those fields in UI - so that at the ned I have one row per user in Calendar with the most updated values.
This is how I set up my workflow:
I created 1 modify a thing and 1 create a thing:


My issue is, the data fields don’t get changed - workflow just created a new row for user even if user has already put some values and just wants to make changes:

As you can see in image above, there are several rows for the same user.

What am I doing wrong?
Thank you