Xiaomi India — Redmi note 3 not charging while on status

Address:	Faridabad, Haryana, 121006
Website:	www.mi.com/in/service

I have purchased redmi note 3, having an sim 1 imei no. [protected] and sim 2 imei no. [protected] from flipkart on[protected].
Within a month of purchase, it stopped charging while in on condition, if i turn it off and then try to charge it then charging process is working pretty fine.
I have to repeat process again and again to use my phone.
I have contacted flipkart regarding replace a defective product and they are saying that they have the policy of 10 days replacement only and adviced me to go to authorized service centre.
I went to service center in sector-14, faridabad (121006) they checked my phone and said i have to leave that for more than 10 days to resolve the issue.
Why should i leave it there, why can't they bring in the part to be replaced and then call me, so that my bussiness won't get hurt. They even refused to give me an another cellphone while my phone (Redmi note 3) is in service process.
It happened to my previous phone also which was xiaomi mi4i having an imei no. [protected], which i had pruchased from amazon for 10099 rs and they asked 8000 rs just to change the faulty part. This is totally insane that a single part is worth almost 90% of total phone worth.
I got it done in 2000 rs via random mobile repair shop and is working fine till date.

Please help me regaring my redmi note 3 phone issue stated above.