******** debit order by Fnb

i had bad service at Fnb,i saw a huge amount being debited off my account without my knowledge.i visited the branch call call centre 9n the 26/01/2019,i enquired about the unknown debit order ,i spoke to Evangeline Damons who is team leader,she advised i had missed installment in April 2018,i ask why was i not informed and they just took a huge amount without getting my consent,she explained i have been sent sms and i have been emailed bank statement it was my responsibility to call them and arrange,i ask why such huge after so many months not being contacted,she claimed that the company has right to debit the arrears if client owes,i told her i also work for bank industry no company has right to debit whatever amount without agreeing with client 1st and debit a reasonable amount,i aksed for refund she said she wont because i owe them ,my question is why is the amount debited not even the amount i missed out on payments,she said they have been taking small amounts from my bank,then i ask why they decided after so many months since April 2018 to take lump sum that i did not even budget for let alone consenting to it, i need a refund of this money this was not agreed to by me with Fnb,am peniless now the company is doing negligent debits without getting permission from the client.can justice be done here please