Cancel debit order

I've been trying to cancel a debit order for the last 4 months and after 10 emails it's still not done. I get a reply back every two weeks from my email being sent from different people with different comments. They don't read my emails. If I was in South Africa I would have strangled someone by now. They take money to stop my debit order, but my debit order is still going off. Due to this, they will leave me no other option to transfer my money and close my bank. Just to advise Im not living in South Africa, I'm in New Zealand