Afraid you need to re-install your ROM. Until you can do that, you can e.g. use OpenContacts from F-Droid. This is an addressbook/dialer that comes with its own contacts storage no other app has access to (privacy-focused), so it should work in your current situation.
You could try Tasker
It can be a little intimidating at first but there are lots of guides online for automating stuff, including this one for sms auto reply.
automation app from playstore is exactly what i use for tracking my kids. i send sms with specific text "where are you" and receive auto reply sms with location (to my specific number only)
found this in changelog to my favorite automation app
Due to new Google Play policy restrictions to prevent apps accessing the SMS inbox:
- Removed monitor inbox ...