Debit Order Still Not Cancelled Over 2 Years Later

Good day,

I cancelled my Cell C cellphone insurance policy all the way back in 2014/2015 but as I was going through my bank statements I noticed that I'm still being debited an amount of R235 every month!! When I try to call the numbers on the documentation I get no answer and the people at the stores say they cannot assist. I've tried cancelling the debit order but my bank says I have to do that with Cell C Insurance (who I cannot get hold of!!!). Please give me back my money and stop debiting my account without my authorisation!!