Urgent

I have a feeling that someone is using our account to purchase goods online, yes sometimes I forget to log out of my online account but that doesn't mean it gives your staff the right to use our account. We pay over R2000 every month yet this account balance doesn't come down. Yesterday it said I could buy for R5577, this morning it says R4400, yet I haven't purchased anything. I would appreciate it if management can look into this problem that I have.