Hello,

Did you log in here

https://www.o2online.de/entertainment/wallet

and tried to cancel it there?

Hello @Ariobarzan.s and welcome to our community 

Have you tried canceling the Unlimited Games with the help of the link @Der Knuddeler has posted?

If you don’t want any third-party-subscriptions to be billed with your mobile plan, i advise you to block these for your SIM card. You can do that online in Mein o2  Third party services

In case you still need help or have more questions on the topic, let us know 

Kind regards, Rebecca