Faulty Watch

I had purchased a Reebok watch worth RS 10,000 which was on a sale for RS 6,000 from the official distributor of Reebok from DB Mall Bhopal.The watch is running slow, i.e., 1 second of that is watch is slightly more than normal 1 second. But slowly over a day, the seconds add up and there is a time difference each day. I had got a 1 year warranty card but it was not filled. Now the dealer is saying that warranty is not valid as the purchase was made on a sale!!
please help.

Hamdan Iftikhar
9009976336
ID- hamdaniftikhar@ymail.com