My brother and a cousin bought this laptop almost a year ago. So it's possible that your laptop has been in the shop for that long. Know that you have to do a discharge/charge cycle with the laptop at least once a month to prevent the battery from losing capacity. I guess no one at the shop did open the box, just to do that with every laptop they got in store... A Li-ion battery has 2 years of useful life, sometimes it can be more if it is a great quality part.
Sorry my friend but you'll have to buy a new battery soon enough. This time check that it is less than 6 months old (the date is printed on the sticker).