Debit order still going off after cancelled 11 months ago

In December I cancelled my debit order because my caped amount of 1g for 99 changed to R500 pm so I had to pay the amount and in Feb I received a cancellation sms. But the debit order kept comming of ..I complained and was told to wait as their billing debt was exoeriencing problemms which I did 4months in a row then I got someone who said I must send proof so I sent the itemized bank statement and emailed it then I called again and I got a oh you didn't need to do that they are busy sorting it out that was Sept now it is December and another debit order went off I would like my money paid back and the debit orders to stop. Today I called and am told o my Wednesday a manager will be in I am so frustrates and annoyed I want to go crazy.