The related invoiced charge has not been reversed and Fusebill is collecting on the currently unpaid charge.
Fusebill separates invoiced charges from payments. As such, refunds are separated from reversed charges. This is so that credits can be issued to customers in order to be applied to future invoices. If the intention is to return the funds back to your customer then the charge must first be reversed so that the system will make no further attempts to collect that charge. This approach gives our clients more flexibility and control.
Read more about refunds, reversals, and credits.