After you log into your Koinim account, click on the account name which is on the right upper corner. You can view your current and past Koinim bills by clicking "Bills" on the opening panel of "My account" option. If you wish, you can download your bill in PDF format by clicking "Download Bill" sign on the right side of the page.
Your Koinim bills have 7 days interval. Your bill is sum up of all the transactions you made in 7 days. The amount on the billing screen is absolutely not an additional charge or debt.