attempting Self Serve as reliable payment method using bank account

Using Self Serve, attempting payment using a Canadian bank account isn’t repeatable nor reliable. On two prior monthly occasions the process was reasonably successful albeit clunky and awkward inputting banking credentials for recognized access doing so. On this successive occasion the process entirely fails, and no other help is reasonably available that doesn’t otherwise redirect to other invasive costly processes. Is there a reliable way forward that achieves successful Self Serve payment online using one-time payment method using a Canadian bank account link that Koodo repeatably honors recognizing valid account access?