Lenovo — my laptop yoga510 not working properly

I bought the lenovo yoga510 at a price of rs.63000 last year only and honestly speaking, it's working worse than a 5 year old normal ranged laptop.
1) there's this problem with the lcd screen which goes blank anytime and the laptop then needs to be restarted.
2) despite having very less apps and no softwares it lags all the time. I don't even feel like switching this laptop on.
3) and now, one more problem has occured, speakers not working!!
The condition of my laptop is amazing and i keep it with the utmost care, but still i dont know what's the problem. I am sorry to be such harsh but that's the truth. All the lenovo yoga products have this issue i guess. And if not all then atleast y510 ones as two of my friends also use the same laptop and they bought it even after me, and both of them have lost faith in the company as there have been the same issues which i mentioned just now with both.
I kindly request you to do something about this issue, either change my laptop, replace it or do whatever you can, but please do something helpful and needful otherwise i would be forced to take a strict action against the company as i have seen these issues with most of the lenovo products.
I am really fed up of my laptop!