Dell — Dell inspiron 15 model-3542 company refuse to replace my system or refund.

Website:

www.dell.com

Hello sir i have bought dell inspiron 3542(service tag :4JF1582) in month of june and my system is not working properly. Just after 2-3 days i found right speaker of my system defected and there was heating problem in my system and system restart itself.I inform this to company and they replaced motherboard and speaker and fan, and they applied cooling paste 2 times but i am again facing same issues.And also there was battery drain problem.now i want refund from company but they are not ready to do so instead they are asking me to replace the motherboard again but i dont want to re-open (4th time) my system.i am totaly harrased by dell and disturbed by them. plzzzz help me sir i want refund or get my system replaced..
thank you