Debit order off on the wrong day

I want my policy cancelled with this company with immediate effect. I see that there are other complaints about exactly the same thing. I gave the authority for the debit order to go off on the LAST day of the month. They tried to put the debit order through from the 24th April 2015. When I contacted them, an arrogant consultant (I didnt take his name) wouldnt understand why I wanted my policy cancelled even after explaining my utter dissatisfaction, he just wouldnt take no for an answer. He kept asking but why? And \He cant see the problem because it has gone off!"I do not see why I have to explain myself over and over to someone who I do not know. Yes"