Cancelled account, but received another bill

Hello,

I called and cancelled my internet service on November 16th. I received an email confirmation stating that the cancellation had occurred, with my last day of service being 2024-11-16. When I spoke to them on the phone, the representative told me that I would have $17.52 to pay for the prorated Nov11-Dec10 billing cycle, which I paid on the online portal. Everything seemed to be in order: in the upcoming charges section, it showed my estimated total being $0 between my $17.52 payment and the refund for "services removed". But now my online portal is showing a new statement for the the Dec11-Jan10 billing cycle and states that my account is past due, seemingly not recognizing my cancellation at all. Can someone please help me with this?