Poor service

I chatted to an agent last month requesting a change of my bank details, the agent confirmed that the bank details have been changed however, it would be too late to change the debit for May and this would only take effect from next month (June). To my surprise, the debit order was requested from the new account and not the old account as confirmed resulting in the debit order being returned. I find this to be highly unprofessional and inconvenient. This is unacceptable. Poor service.