Realme - Faulty piece delivered

I ordered Realme * pro from Flipkart.I got this on **/**/** at *:**PM.Due to busy schedule I'm unable to open it at that time so I open it late late night.After using it for **-** minutes my phone suddenly get shutdown.I put it on charging but it didn't respond.I kept that on charging about *hours but it is not responding.So I packed the mobile and raised the replacement of mobile at Flipkart.But they didn't approve replacement and send the technician.
Technician visit *- He came late evening and use my charger but it didn't respond.Then he use its charger and kept it for five minutes and phone starts .Then he use my charger and my phone is charging with it.I asked him reason then he said due to the mobile kept in warehouses due to which charging becomes Negative sometimes.
Next day phone hangs and shutdown suddenly.The phone starts after * minute.Then I raise complaint again.
Technician visit *- New guy visited and he said use the device without back over(which I get with phone) & without screen guard (which is placed already on the phone). According to him this are the reason for hanging/lagging in device.
(Both the technician do not have technical skills).
Two days after, I purchase Boat *** earphone but it is not working in my device.It is working well in all other devices at my home.
Then I raised complaint again but they are delaying it again and again.
I am badly harassed by Flipkart.I want my refund now.I don't want any kind of relation with Flipkart.
Odered from - Flipkart
Delivery date - **/**/****
Order id - OD******************