Debited on the 16th of the month

With NO notification whatsoever, Vodacom debited my account today 16/12/2015, as opposed to the usual date. <br> I find this totally unacceptable and due to this, it has now taken my current account over my overdraft limit resulting in further bank charges. I have been a vodacom customer for 12 years, and have never missed a single payment in all this time. To debit accounts early without notification is not on!