Security problems

What a situation! Good thing you are getting the messages where you can say - Do Not Allow. This link below offers some helpful advice. I’ve copied suggestions for what I believe you should do immediately. I hope this helps put an end to the problem.

If you think your Apple ID has been compromised - Apple Support

Gain control of your Apple ID

1. Change your Apple ID password
2. If your Apple ID password has been changed by someone else, reset your password.
3. Go to appleid.apple.com to update any of personal or security information that isn't correct or that you don't recognize.
4. Check with your email address* provider to make sure that you control every email address associated with your Apple ID. If you don't control an email address, work with your email provider to regain control or use a different email address.

* In China mainland and India, you can use your phone number as your Apple ID.

Sorry it did not help. Please contact Apple directly. Tap Support at the top or bottom of the page.