We sincerely apologize for this issue and the impact on your business. The team is working diligently to reach out to each impacted customer to help resolve the issue and process the refund.
Submitting a support ticket with a screen shot of the debited amount from your bank statement (suppress/hide any account information) is likely the quickest way to resolve outside of rejecting the transition, which you noted was not possible. Our team is actively working those tickets and will confirm via email once received and reviewed. You may submit a support ticket here: https://support.fattmerchant.com/kb-tickets/new
Thank you again for your patience as we work to remediate this issue.
Sincerely, the Stax Team
Sorry to hear this is happening to you, but not surprised. Consult a lawyer, I'd say.