• H-form under vat

Manufacturer has sold certain goods to a company "A", "A" represented that the goods will be exported, and claimed exemption from VAT. "A" expressly mentioned 'against H form' on Purchase Order. Thus Manufacturing/vendor have not recovered "VAT". 
Even after one year "A'' is not making available the H-form and other documents to manufacturer.
Now Sales tax officer are asking the manufacturer to pay the VAT with interest and penalty. 
Buyer "A" is saying Sales Tax Dept is delaying the issue of H-form. Sales Tax office for both Manufacturer and buyer is in same District.
What remedy is available to manufacturer? 
Can Manufacturer sue the buyer "A"? in which court file the?