Cancellation Since March,Still billed until August

We have been trying to cancel our contract with MTN since March 2015 (Email Correspondence as evidence).We have called in numerous times, sent numerous emails, We sent our office administrator to evens go as far as making a turn by a shop they did not help as they say they do not do cancellations at the shop. Luyanda of Customer Service told us our last bill was on May 2015 and we were requesting email confirmation, no response. Our best solution was to cancel the MTN debit order by our Bank due to them failing to cancel our account since March 2015. We managed to put a stop on MTN's Debit order for 3 months until they decide to call us back. We did not use the numbers of the account but they have been billing us for them. After I mentioned that we are placing a stop to our Debit order, MTN requested more Documents in July from us, we filled it in and sent it . After reminding them to send email confirmation of the cancellation and the stop to our Bank debit order they finally responded with an email.They are still expecting us to pay our last bill in August after all this bad services due to their \30 day Notice Period"may I remind you that we cancelled in March. This is not fair"""