Debit a cancelled contract account

I was due for an upgrade at 8ta in April 2015 this year but decided to cancel that account and open a new one.They debited R580 from my account which was suppose to be cancelled 2 months back already.I did inform the nearest store and they opened a case however after their investigations i received a call today and that lady said they do not see any payment from my side.I inform her that the reason why the store opened the case is because they saw the payment on my account on their system.the lady then said i should sent my bank statement reflecting the payment.what is that??How come it does not reflect on her side whereas the store did see and iopened the case.I am sick and tired of Telkom/8ta and their bad customer service.I have been with then 2 years now but i have been experiencing the same problems over the years.