MVAT refund for FY 10-11 & 11-12

I have pending MVAT refund for FY 2010-11 & 2011-12. My CA missed to file Form 501 in time. I had done followup to MVAT department in past also, but every time just received fake promises of initiation of voluntary assessment. I had sent letters to The Hon. Jt. Commissioner also but no response from them. What further I can do in this case as refund is of around Rs. 12 Lakhs kindly suggest.

Regards,

Mangesh Chitnis