Ridiculous charges and bad attitude

I received a call from your agents that my account is on the negative and I owe you almost R300,how can I be charged so much for two debit orders that returned unpaid on a student cheque account, I tell the agent I will go to the nearest branch and sort it out as soon as I was able to, yesterday I got another call from your agents who was very rude to me, he asks me why I haven't made the deposit to bring my account to a positive, I should of known there would be charges if debit orders go off and there are no funds in the account, I tell him I'm aware of that, what I don't understand is why I was charged so much,I was never informed I would be charged such high amounts, then he tells me it's not Absa's problem to notify me how much I will be charged if a debit order goes off, I should of put money in the account before they went off in the first place to avoid charges, is this how Absa conducts services, by not giving clients all the information and then telling them its not Absa's problem they didn't know all the information, because if that's how it is, I'm definitely closing my account and finding a better bank!