As per our commodity code tax should be tnvat 14.5%

As per our commodity code tax should be vat 14.5% in tamilnadu but we have got GO from tamilnadu government for concession rate of tax 5% for supply to defence. So, we claimed 5% for all defence sectors throughout INDIA. But while audit,  tnvat they telling that it is eligible within tamilnadu and not for other states and asking to pay the difference tax of 9.5%.  But we collected only 5% and now we are in burden what to do? Kindly clarify.