Debit order date not changed after 3 months

I have request my debit order deduction date by changed from the 25th to the 1st as I no longer get paid on the 25th.<br> <br> Ref ***3<br> <br> Request sent on 11 November 2015<br> Followed up on 25 November and this was not changed<br> Followed up again on 27 January<br> <br> Followed up again on 19 February and was told that my next debit order date will be the 1 March 2016 but I was debited on the 25th!<br> <br> Every time, someone responds and says that it has been changed and its not.