We're sorry that you're experiencing this issue!
[Mobile app]
We would like to suggest reaching out to Google Play Help
https://support.google.com/googleplay/answer/4646404?hl=en&co=GENIE.Platform%3DDesktop
or Apple Help Center https://support.apple.com/en-gb/HT201266 for better support, as all payment processes are handled by the app store itself.
[Web]
Please kindly reach out to us through our Help Center. We will check the payment process for you and will get back to you as soon as possible with a solution.
We hope it gets resolved soon so that you can join us for the uninterrupted webcomic reading experience!