Money missing for account

Additional money has been debit from our account (R1800.00 and some change) which i cannot account for. Upon calling the call center, I am informed that no information can be provided to me. Now i am very careful about where and how much I spend at various merchants and can account for every cent of our money and know for sure that this additional debit should not be there. I am now sitting with a sick toddler and no access to my money to get him to the dr because no one will assist me. FNB needs to fix this.