Unortherised deposit order

This is the second time FNB has deducted money from my account. The latest being R1, 400. They say there was some glitch on there side. I received no notifications or phone calls ect. Fnb has been great u till this. They have now put me In arrears unless I deposit the money. There is no evidence at all in transaction history or details or statements that this has even occurred. The help line was rude and I've recorded all phone calls. I urge those with fnb to watch you app carefully and those opening account to maybe go to another bank. Their service was great but has become **********. The helpline women should have some manners and help should be given