Ted here from Shopify, thanks for reaching out to us and for letting us know.
Do you know if another store was created by mistake (or a trial store) with the same email address? I'll need to take a closer look at the account to see why you received the invoice.
Please keep an eye out for my email and if there's anything else I can help you with, I'm happy to help!
Thanks for letting me know! I've emailed you there with some more information for authentication reasons. Please reply back to my email when you get a chance!