Incorrect Information conveyed

I honestly don't know what to do with Nedbank anymore 2months back I called their Call Centre and spent 20 good minutes on the phone with the Agent regarding my credit I asked this lady to change my payment date to the 25th of each month from the 21st because I get paid on the 25th. I realized that it was not changed I called yet again I spoke to an Agent I just forgot their names, he advised me to say whether I change the payment date or not its still the same because areas can only kick in after 15 DAYS now all of a sudden i received a statement on the 25 Oct with a huge amount of money that I'm owing. Why am I on areas every month. When I took the credit card I was told that I won't be liable for any areas if I pay within 55days and a once off payment of service fee now that ridiculous service fee is appearing each month. I believe this people who were advising me are FIAS accredited they wouldn't lie to me. Now can someone from Nedbank look into this and come up with a better solution because there's no ways I'm paying that money. After being with Nedbank for 7yrs I'm afraid this is the end of us I've just grown out of love for this bank for so many reasons.