Vat quary

Dear friends,

I have an Quary regarding vat. we have purchase some material of Rs.50,436/-( including cst) from Chennai they charged as cst @ 2%  at time of issue of Tax Invoice now we pay them full payment of Rs.50,436/-.they put a mail to us regarding issue of 'c' form Bt we are not an Registered Dealer under Vat so we can't issue 'C' form to them so they asked to pay them full vat @ 14.5% asper channai govt.

Is their point is rit to ask about full Vat @ 14.5%? or there is an some solution with the above issue

Plz anybody help in this situation.