Debit Order After a cancelled contract

My contract expired on the 06/05/2015, I phoned 808 to cancel the contract on the 08/05/2015. The contract was not cancel, on the 14/05/2015 MTN sent me 300 MB and 200 minutes. I phoned for the second time to ask why is my contact not cancelled like I requested, I was told about a long waiting list. The third time I called was on the 23/05/2015 and the next day the contract was cancelled and my line was migrated to pay as you go. MTN have been debiting my account after I have cancelled the contract, every time they do so, I have been reversing the debit order as I don't owe then, I requested the contract to be cancelled, I got a call ***.I have emailed [Email Removed] on the 25/06/2015,no reply. My data bundles where taken from the and the remaining balance, which I was aware was going to happen during migration. On the 25/05/2015 I bought 1GB for R160.00 I was unable to use the 1GB plus the 1GB free that I got for free when I purchased the 1GB. on the 25/06/2015 the 2GB expired without me using it as my phone was not connecting to the internet because MTN messed up during the migration to Pay as you go. MTN must stop debiting me & refund me for my 1GB.