Asus ROG 5 - help for refund of asus rog phone 5

I bought Asus Rog phone * about * months ago.In starting it had heating issues for which I called customer care roll free number. They tried to help me but it was not that good. After about * months the device turned off automatically while I was on call. it was like dead totally. I went to the service center in Nehru place New Delhi. First of all the staff is not supportive. They had my device for about one week. After that when I went there to take my device back they told me that we replaced the motherboard. I was happy to have my phone back. After some days I started facing the issues like network issues, auto shutdown, auto restart, and now fingerprint also missing. I called customer care number for many times everytime they promise me to arrange call for replacement but it's not working. Now I am totally out of mind I don't know what to do. I bought this device from my two months salary. I want refund for this. help me regarding this if you can. I want my money back. I want only refund now.