Lenovo — Lenovo laptop issue

Address:

Chennai

Have purchased the laptop before 2 months back via Amazon website, Now i lot of issues are happening in my laptop( System reboot issue, Automatically gets switched off, Slowness, Os got corrupted),

I have visited the Lenovo laptop service center at [ Location: Chennai- Ashok pillar past Saturday (i.e.Apr2nd)] they have done service too, now today also the same problems are happening again and again, i have not satisfied with the laptop service what they have been provided by me from their end, help me to resolve the issue or do some alternative action like replacement or money return

My laptop serial number as below;
PF3BN3YS