Dell India Private Limited - Defective on Arrival Dell Vostro 3401

Hi team,
I have purchased new laptop from Whitehatjr for coding class. They have sent me Dell Vostro ****, the laptop i received on **th April **** and was physically fine. When i started laptop it took me * hour to start but i ignored that considering *st time reboot. But from next day when i start that laptop again it takes lot of time to start and i am not able to work on that laptop because it is very slow and not responding. I complained the same to whitehatjr, they tried fixing the issue but could not able to do it, then they escalated to Dell technical team, they also took the laptop on remote and installed updates and driver updates and ask me to keep under observation for ** hours. Still after that also laptop is not working fine again dell team took a remote and run a diagnostic test in which they found *ne or more critical error and then again they are asking me to arrange ** GB pendrive and install new windows. So i am not happy with this laptop and requested whitehatjr and dell team to please take this laptop and process my refund as this new system is giving so much problem which i have not expected. But they now denying that we will not process refund but we can repair your laptop. Since this machine is arrived defective then how can they deny for refund, if i got this problem after a month or two then they can troubleshoot. But they are simply saying no and it seems they cheated me as the manufacturing date is also *** days. That means old piece they delivered to me with high amount of money.
I need your immediate support to get my money back so that i can purchase new laptop for my kid.