Seller refuses to provide bill, is rude and trying to extract money unethically

I purchased 2 ACs worth INR 60,000. Paid 10,000 as advance and at time of delivery started following up with the seller. It is at this time that the seller started behaving mischievously and rudely. Nevertheless I transferred the balance amount so that the products are delivered. The seller did not give any update for 4-5 days and also did not respond to messages. Finally he delivered the products but did not provide the bill. He insisted that i pay three times the delivery cost that was discussed if I wanted the bill which i refused. To which he threatened me that He will make me come all the way to his shop to pay the delivery charges. What actions I can take to make sure I get the bill. I have no problem posting the genuine g delivery charges but this guy has been untrustworthy and very rude all the while.