o2 is charging me double monthly

My gymondo contract was canceled on the 17th and still have high bill after, and I want refund of all the gymondo I paid for from the beginning of my contract. 

https://www.o2online.de/kontakt/

Send your objection to the invoice via the contact form. You can only do this for the last two invoices (8 week limit).

A cancellation on the 17th will still appear in the current invoice as invoices are issued retrospectively.

I really don't understand you. Pls can you explain better?

Hello ​@Yousef22,

welcome to our o2 Community 🙂

I have refunded the payments for Gymondo within the last 8 weeks 🙂

Best Regards,

Gerrit

I don't see any refund. 

​@Yousef22 

You will see the refund on the next invoice, at the latest on the invoice after next.
It will then be listed there.😊

Best regards
Daniela

Hello ​@Yousef22,

I would like to ask whether the answers here have helped you and whether you have
received all the information?

If you have any further questions, please let us know. 😊

Best regards
Daniela