ARGUMENTATIVE CALL CENTRE AGENT

I called 084143 to cancel a contract which I have had for more than a year - but never use. After waiting 20 minutes a consultant finally answered. He proceeded to ask me the usual security questions which I answered correctly. He then asked me which date my debit order goes off. This I could not answer at that moment because as a business owner I have about 50 debit orders - I CAN'T BE EXPECTED TO REMEMBER ALL THOSE DATES! Instead of asking another security question an argument ensued, he then told me that I answered a question incorrectly and that he has spoken to me long enough as he is only allowed 5 minutes per call. He then slammed down the phone in my ear. I thought I will give him a bad rating, but he also cut me off from the \Rate my Service Customer Survey"that usually follows. I phoned back to speak to a supervisor but they said I will be contacted by someone shortly. I am still waiting. - I AM EXTRMEMELY DISPLEASED by the way I was treated after waiting 20 minutes for service and being friendly and polite to the consultant. """