Fnb bond repayment

I have been with fnb for long time but now its just problem every month and ****s with empty promises,I have a home loan with fnb and they doing salary deductions,every month they adding extra amount which i don't understand and they promised they will rectify that but nothing even now..they said it was their problem but now its now my problem,how can my bond be on arrears while they do salary deduction? They don't take this matter serious, one of their consultant called me and said she will write an email apologizing but even today nothing, they said they fix the error of monthly repayment but nothing.please help.