This answer is based on the question asked and the background provided. I am making the assumption the indirect rates used in your original billing rates were understated, which you found out after the DCAA audit. You have now submitted an invoice to the contracting officer using the actually rates from the DCAA audit and have not heard back from the contracting officer, who I am assuming is still the person who was originally the contracting officer on this contract. You have followed the process for getting paid, but have not been paid. You might want to call the contracting officer and ask the status of the Government payment to your company and whether they need any additional information from you to make the payment.