Unfair internet banking practice

I want this complaint of mine to be a warning to other people who do internet banking with FNB. The warning is that when FNB customers are doing internet banking payments, it is imperative that they triple check the account numbers they are depositing funds too is absolutely correct because if the account number is incorrect you stand a good chance of loosing those funds. This is what happened to my son and I. Judge for yourself if you think this is fair practice. My son owed me R 6000.00. He did a FNB Internet Banking transfer to my account which is another bank. He incorrectly left one digit in the middle of the account number out. The account number should have nine digits in it, he only had 8 digits. The short story is FNB added the digit 0 to the front of the short digit account number, thus making it a valid nine digit account number, so the funds went into that account. The owner of this other account spent the funds and refused to pay it back. The bank (FNB) claim that my son put the incorrect account number in so he is in the wrong not the bank. The problem I have is the funds did not go into an account with the short digit account number my son put, but into an account with the extra 0 digit added by the bank. Even more disappointing to me is that the bank (FNB) has somehow convinced the banking ombudsman that this is an acceptable practice on their part. I am interested in seeing people's comments on this issue.