Debit Order Change Request not Happening

I have been trying for 2 months now to change my debit order date. I have been to a store (Cradlestone) and asked to update my debit order date to be the 1st of every month. This did not happen, then I sent a request via email to Customer Care, with no response from them. I called 135 and after numerous attempts managed to speak to an agent, and she confirmed the debit order date was on the 1st.... Gues what... it is not. My debit order went off on the 27th!!!Really terrible service!!! Can someone please assist me in changing my debit order date to be the 1st of every month?!?!?!?!