Vat in maharashtra

Respected Sir,

I had purchased a flat in dombivali in 2010 and now the builder is asking to pay a vat of Rs. 85000. while purchasing the flate no information was give to us with regards to the vat charges for the flat. The builder is asking to pay in his name the VAT charges. How we can confirm, wethere I am suppose to pay the vat to builder. Is there a option to pay to the goverment directly, if there is any, which I have to pay?

Please help me to understand, Is there a way, if I could pay in parts as this is a big amount for me. 

Thanks & Regards 

Prasad.