Stop order change

I requested for a debit order date change on the 8th and sent through the required form and got no response within the 24 hours stated on the auto response. I made a follow-up on the 11th I was told to check again on the 13th and the agent confidently told me everything has been sorted and the next debit date will be on the last day of the month. On the 25th I get a notification that my account was debited, made an enquiry the next day I was told no the 3 people i spoke to were supposed to log a request for the change to be done even now I'm still waiting for that to be done.