Doubt about cash discount and trade discount

Wanted to ask while calculating final amount with vat should cash discount be calculated after applying vat or before vat. I bought some product.And the agent calculated total value with vat and than deducted some scheme discount value and trade discount over it. According to me first buy price comes.Than any scheme discount deducted.Than trade discount deducted.Than Cash discount if any and than vat applies. The agent applied vat first and than discounts. Because of this for a bill of sum 49000 there was some 400 rupees difference which was i paying more.