FNB failed to assist me rerversed an authorised debicheck by cell c

after standing on a que for 2 good hours ,Fnb couldnt assist me reversing a debocheck for cell even though i never authorise such debit ,im left with zero on my account they telling me to call cell c ,and cell is telling me stories ,i have seen some back manage to reverse debicheck ,my failed i am moving my account to somewhere else they care anout customers ,surely someone can authorise that transaction a whole phone contract of 2800 form 342