I am assuming the Charged taxable sales is your GST charged on sales and your GST payable is a subtotal account to show the balance owing or refunded. What is the G1 refundable and the GST Refundable accounts? Do they both have a balance? How are these set up in the taxes section?
You can go to the balance sheet to retreive your totals or go to Reports>Financials>General Ledger and select all the GST accounts and put in your start and end dates. This will give you your detailed information.
I would first find out how these accounts are set up then go from there.
HTH