I have this exact same issue. My nickname "nat" can be short for both Nathaniel and Natelie. And apparently there is a Natelie with the same last name as me, and she seems to use my email address with a dot in it. I've been getting frequent flier emails, school emails, and more. Whenever it is an automated email, I contact their customer service and explain the situation, then unsubscribe.

If the email seems to be personal, I respond and ask them to have "Natelie" contact me, but she never has.

I agree with you, it's very frustrating. I don't have any solution, but I'll be following this thread closely.