Unauthorized debit order

Ive been with FNB for more than 5 years, but it service sucks... I have been disputing a debit order that was not authorized for 4 months now, asking them to stop it, charging me for reversal, every month i should get stressed because i have to call their customer service for one and the same thing, i emailed them on Saturday 31st, but didn't get any response. As much as i love FNB, i am thinking of switching all my incomes to different bank, because anyone can have access to my account as much as they want and i have to pay for it.