Debit order changing every four months!!!!

<p>For the last four months i have been trying to change the date of my contract phones debit order date. I went in store, online and even phoned. Everytime the consultant will tell me or even show me on the computer that the debit order has been changed but come month end the debit order is still on the last date of each month and has not been changed!!! This reflects negatively on my personal account and is unaceptable. Can some please assist in changing the debit order to the 15th of each month without any delay. Thank you</p>