incosistency / unfair service

I am very disappointed with their service. They honoured a debit order that was previously cancelled which took all my salary and even more than what i had on the account and left my account on a minus of 1400. The worst part is that they normally dishonour debit orders when you are short with 100. When i sent a request to reverse it they told me they no longer do reversals even though this was stopped previously.