Lenovo — ideapad 500s not working properly

Have purchased my laptop ideapad 500s on 19/07/2016 from alco info - tech pvt. Ltd. E-mail, park street, kolkata - 700072.
From the beginning i am facing the similar issue. My system's screen goes into black on random basis. It has no pattern and not any timing concern. Only screen is going black / off but system at on stage. Everytime i am forcefully suttdown the system and starting again.
Many time i have complain over the phone using customer care number.
Even many time i goes to service centre.
According to service centre technician no software problem and no hardware problem.
If there is no problem they why problem is coming again and again.
Why should i suffer everytime. From the beginning i have not used my laptop properly. I am a working person with newlly defected laptop.

What should i do. I don't know about knowledge of your technician.

Just inform me did i always suffer and haras by this laptop and your customer support agent who are not able to help.
Everytime they giving me some excuse.

Is this your service. I have never able to use this laptop properly. And i don't think i will.

Please track my all complain using my mobile number you will know about my problem and also got to know how much i have suffer.
Mobile number : [protected]

Thanks,
Rupa kumari