Multiple reminders being sent to provider

Hi, our site, along with 16 others on this wordpress multisite installation, are sending reminder emails out to the provided in 10 minute intervals starting at about 4 hrs prior to the appointment and then stop after the appointment.

We have concluded that it is the provider who is receiving the reminders and not the potential client, but this is still annoying for the provider. See the attached screenshot for the email log and you'll notice how often the reminder emails are being sent.

[image pos="0"]

Also see below for the notification settings:

Thank you in advance!
30 Lines