A lot of systems seem to silently fail on Firefox - my broadband supplier's website failed at the last step of the onboarding process. I managed to get charged for installation (connection by the network operator, UK) twice, have onboarding emails sent, but not have the appointment in my account.

Used Edge, went through completely.

Can't guarantee it was Firefox/browser issues. But this is not that uncommon an occurrence.

I suspect it is the bank who are at fault.