Failure to change debit order details to a new account

Pathetic service. I simply called to change my banking details but am being told stories. Tomorrow when u debit the account and not find funds ul sort yourself out because i am not going to deal with rude advisors who hang up on me and require letters just for change of account number?? *** i mean really? I am going to somer change to absa and move my business. This ia the 3rs time am calling and am told to send statements? For what? Its my account I confirmed my id number. If u dont want its fine