question about game sub it charged me 0 eu

so guys last month i bought ffxiv+hw and got free 30day sub and today it was last day so i bought 30 day normal sub without 8 characters and it charged me 0eu so i wanted to know why did it charge me 0eu.

heres the mail i got

Thank you for using the FINAL FANTASY XIV Mog Station.
This e-mail has been sent to inform you that your service account for FINAL FANTASY XIV has been registered successfully.

Date: 06/10/2017
Service Account Name: FINAL FANTASY XIV
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Services: Entry
Payment Method: Credit Card/Debit Card
Billing Cycle: 30 days
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Payment Amount: EUR 0.00

Shhh! Keep it to yourself! Enjoy (what seems to be) the rare bug!

aka rare ban lol

When you register a subscription it doesn't charge you immediately unless the current sub end first. If I register a subscription before my 30days ends it doesn't add up another 30 days unless the current one finish first. This is why I get mails with 0 eur charge then it proceeds the normal charge on last day.

o thanks :o