Welcome to the community!
I understand you have closed your account. It's possible that the bill was generated prior to your account cancellation and may not be relevant anymore. However, you might consider verifying your account status to be sure.
You should note this forum is community-driven and not intended as a venue for customer services. If you would like to verify your account status, you would need to contact customer service. In addition, they can also be contacted via Live Chat, Facebook, or Twitter. Those methods can be accessed via the contact page posted above.
Hope this helps 😀