Tax to be levied on the goods sale return value

We sold the goods to general customers and vat dealers with in the state of andhra pradesh. On every month we filed the vat return, in that return we deducted the goods sale return value from sales turnover for the prescribed month. Now the Department personnels has conducted the vat audit, they are raised the tax amount for Sales return value. How can we pay the tax for the sale return value. Is there is possible to be levied tax on the sale return values. Please guide me , how to overcome the current situation.