HP India — Printer

Address:	Gurgaon, Haryana, 122011
Website:	www8.hp.com/in/en/contact-hp/office-locations.html

HP gave an offer in the market that with the purchase of the printer, they are offering - FREE Cartridges. Invoice & Sticker on the product is attached.
On none, any kind of Terms & Conditions are mentioned.
Now, they are telling me that there was a limit of 15 days.

How could I assume the T & Cs at my own.

They made the Terms & Conditions and chose to keep it in their office and now when I am asking for the offer, they are telling me that it was supposed to be asked within 15 days of the purchase.
How in the world they expect me to assume the T & Cs !!