contact not cancelled as requested

I contacted mtn on 808 in january to cancel my contract with them, was advised last debit order would be end of February, consultant at vangate mall advised me in february as well that it will be cancelled , march I again received airtime and bank account was debited ,went again in to vangate mall and wasted more time in a queue, now its april 21st same scenario received airtime again and am currently wasting my hole lunch hour at mtn vangate mall , I want this matter resolved as I did the 24 months and as a customer have the right to cancel it after that, Im horrified with the service mtn is giving me and have no regrets cancelling all dealings with them. I want the airtime, data and sms reversed (besides the data I bought myself) and want contract cancelled immediately because I am sick and tired of this inconvenience.