UNFAIR PENALTIES

A debit order bounced last night because I had set my online purchases limit lower than my instalment. When I saw the message notifying me about the unsuccessful payment I than paid immediately withing 12 hour and they had already levied a penalty. My understanding is that the penalty is levied only after 24 hours after the bounced debit order. I called the call entre and they promised to investigate and call me back, which they haven't. I need my R290 refunded please.