Got charge for failed transctions

I was transferrinng funds to my home loan accounts from chaque account the transaction failed 4 times. And i finally decided to moved them to savings pocket that was on tuesday morning of 31 of october 2017. Then this morning when i woke up all those funds have succeded and fnb charged me R330. When i ask about the charge they say they honoured they honour transactions while i didnt have enough funds on my account. But the banking app kept saying the system is down.