refused to reverse debit

My name is Josephine Masekela i am banking with nedbank. i had a debit with fonechoice i bought laptop . i had a debit from fonechoice every month and the contract ended end of July. the complain that I am having is that on the 12 November fonechoice debit the money in my account and i requested the bank to reverse. i was told that they can't reverse the amount as fonechoice blocked my money, i told that official that is a ***** because i am no longer having a contract with them, i am really upset with the bank that they is no security any entrerprise can take my money in the account without my authority, I have taken a decision that i will quite the bank if they are not going to resolve my issue.