Irregularities related to credit payments

I've been contacted by the credit department regarding payment, to which I referred back to my statement emailed to me earlier this month, and how much is required of me to pay. Consultant via phone stated the information on my statement was incorrect, and wanted me to confirm an additional payment than required, even though on the statement it says that all costs are included in the original amount expected. This is not the first time they've tried to confuse and persuade me into paying more than required.