Payment of vat

I purchased flat in thergaon, chinchwad, pune area on 20-Oct-2012 (date of sale deed) in resale. The then owner had booked the flat in Oct or Nov 2009. After possession of the flat, in Mar 2013, I found a communication from the builder in the letter box dated Sep 2012 (i.e before the sale deed was done) in the name of the seller asking him to pay the VAT, the failure of which may lead to criminal proceedings and may affect the title of the property. It gave reference of the judgement of supreme court court and govt of maharashtra (till then the vat matter was subjudice). This letter from the builder mentioned that the seller had agreed to pay vat as per the courts judgement if required in future in his agreement. I do not have the copy of his agreement with the builder. The seller did not respond to my phone calls regarding this. Then I sent an email with a scanned copy of this letter to him somewhere between Mar-May 2013 asking him to visit builders office and settle the vat issue. There was no response. I have the sent email in my gmail. Also property tax and electricity bills were not paid. Now I have to sell this flat. I again reminded him for vat payment via email in Feb 2015 this year. He replied that he taken the builder NOC for sale of the flat in 2012 and refuses to pay it. But this NOC was dated before the court and the govt had given their judgement regarding vat and also does not mention that it has been cleared. Now interested buyers for this flat ask to first settle this issue. Result is I am not able to sell it. Kindly suggest about the options before me now. I presently reside in Navi Mumbai.