poor service

I had sent a request to have my funeral cover cancelled, despite my mails cancelling the funeral cover with Everest, they are still debiting my account. I went into Standard bank in Greenstone mall and they advised me only the person debiting my account can cancel the debit order, they can only do a stop payment for 6 months. now I would like someone to explain to me why me as the account holder am I not able to cancel a debt order. the lady at the bank kept me excuses of why I can not do it. so in other words, anyone can do as they please with my account and there is nothing I can do as the account holder. please advise as I am getting tired of hearing it cant be done when it comes to standard bank.