MTN'S PATHETIC SERVICE OVERALL

I am at the end of my contract period this month as far as i know and i had been eligible for an upgrade as per the sms i received only on the 31/03/2015. I did however decide that i will not be taking an upgrade and would like to cancel my contract. I attempted to call your call centre and due to your strikes obviously there was no one to assist me,i went to the store and they said they could not help me. I sent an e-mail to your customer care in MAY requesting cancellation and questioned when my last debit order would go off. I only received a response almost a month later on the 19th of June.For this month i was only credited with R210.00 airtime and 25 sms's, so please advise why did you debit my account with an amount of R399 as opposed to my debit order amount that has not changed for the last 11 months of R389, i do not care if it is just R10.00, i did not ask you credit my airtime account with an additional R15 without my consent. I want an explanation as to why you debited my account with an amount more than it should have been as im not sure id get a response using any other platform to get a hold of you guys!!! you are really putting customers in a difficult situation!!