Account query

I have an account query with vodacom on ********** 356, they ran a debit order 2 days early in March and it bounced back. I called the accounts department on the 9th of March to resubmit it and was told it will go off on friday the 12th on my normal subscription as i wasnt willing to pay bank charges due to that i never signed for an earlier date.

a very rude consultant from Vodacom called me on Monday to find out why i did not pay as per arrangement that i was going to pay in store.I explained to her that i was wating for a debit order to run as per arrangement.She accused me of lying as it goes off within 12 hours.I instructed her to run it again.

Today i called the account department and they insist that i pay for these bank charges as i signed for the last working day of the month not the last day.

please help as i'm really running out of patience with this. I signed for the last day of the month not a anytime before that.