Samsung - Mobile is defective and company is neither resolving nor replacing

The issue that I have experienced was: Samsung Galaxy F** mobile, i have purchased on April **, this model doesn't support *Ghz Wifi, so wifi doesn't show in network list. I raised for Return & refund or Replace Flipkart on ** April, Samsung Technician clearly mentioned me that the Model is defective as *Ghz supporting Hardware is missing from this Model, so even if replaced with same model it will be defective.
But technician has updated to the seller Flipkart that the issue is resolved. So the Flipkart has cancelled my return Request

It occurred on: **/**/****

It is within the warranty and return policy date, i need to return the mobile and refund, kindly help on this, its a hard earned money

I look forward to your prompt response on this matter.

Yours faithfully,

Vinayak Shirahatti

Flipkart Order Number: *d******************