Once you have a contract you struggle your ass of to get it cancelled They keep on taking your money!!!!!

I have 2 contracts with MTN. My one contract is over 2 years and I don't want to upgrade it. Why do I have to struggle to get it cancelled????? I phoned a month and a half before my contract ended on the 14th of October to cancelled it. Yet another premium went of in November, then I phoned again, and they apologize they made a mistake and that I had to pay for November. Now they phone me and said I have not cancelled my contract, Now when I phone. because I cancelled on the 14th and not on the 11th of a month. I still need to pay x2 more payments on data. So Now I have to pay for December and January. Why 2 more months? This is bizarre. I am fed up with MTN!!! how is this fair to any customer!!!!!!!!!