Yahoo calendar no longer syncing on iPhone

Yahoo calendar no longer syncing on any of our 3 iPhones

I have already updated to the latest iOS) and deleted my Yahoo account and added back to my iPhone. I added a Gmail account on my phone and this calendar syncs fine. Yahoo calendar events entered in the browser do not show up in my iPhone calendar. Yet, events I create on my iPhone associated with Yahoo email show up in the browser version. The only way to view yahoo mail on my phone is to use the Chrome browser calendar.yahoo.com. This view is completely unusable.

After an hour with yahoo tech support, they are telling me that I have lost the ability to use the mail app and that is just the way it is. The browser is my only choice now.