What to do?

We've finally got our BAS done; yesterday I received an email from the account with document of our BAS which the account has prepared. All that was needed for me to do was sign the document and fax back to the accountant.

In the meantime we do have to pay the GST owing to the ATO before the 25th of this month or else! Businesses are being used by the ATO to collect taxes from the public and got nothing in return except for the GST claims which isn't much. What to do?