Shocking service from MTN

Probably the worst customer service on the planet, I have sent numerous mails requesting cancellation of a number which is no longer required. I first made contact via the MTN contact page on their website, I received a response via mail requesting me to provide my security answers (really you expect me to put them on mail to you??) which I rep**** to requesting a human to call me as when you call using their 135 number you receive an automated message informing you of how busy they are and then get to listen to chamber music on repeat. I to date have sent 4 mails and each mail gets a reference number and automated promises and then at the billing date I get another invoice. The sad thing is that it appears there is a level of arrogance amongst cell providers.