I received a short email from 1&1’s complaint department today.

Thank you for your email.

I just had a look into the matter. I am honestly not 100% sure as to why the invoice in question was raised in the first place. I just cancelled the invoice and told our billing people to clear the matter up fully.
I sincerely apologize for the inconvenience this has caused you.

If you have any further questions please do not hesitate to contact us.

—
Sincerely,
[name removed]
Director
Customer Services
1&1 Internet