MTN IS A *******

i have had a contract with MTN for almost 4 years now and i cannot say that it was ever smooth sailing . they have always suspended my line at the end of every month whether or not payment was done, i have called on numerous month to have it reconnected , in june MTN workers were striking and a result of that was that there were no stores opened to pay our accounts and therefore having to find other means and ways to get it paid and avoid suspension.On 9th June 2015 i forwarded a deposit slip showingR 200.00 proof of payment and requested that the contract be cancelled as it was ending in August 2015. In July 2015 i forwarded two payment slips for that month and informed them that i had made two payment which would fall for july and august and that they should forward a statement showing a zero balance , i had to send a mail again on the 31/08/2015 as the line was again suspended. i was notified yesterday that i have an outstanding amount of R400 and have no idea where this amount has come from and that a contract needs 30 days cancellation notice, this was ironic as i mailed on the 6th june 2015. now the amount is apparently for the next two months .