Ee exchange offer for Redmi Note 3 is a loss for you.. the person who will get the mobile from you will replace display and battery and will either use it for few more years or sell it at 6/7k (minimum)..
Also, buying a new phone for 5-6k, you will get Android phones with 1GB RAM.. android nu vendi minimum oru 2GB RAM + 16GB undavanum.. athum waste of money aanu.. if you are planning to buy a new phone, need to spend at least 8-9k.. aa rangeil Moto G5, Honor 7C, Redmi 5, Asus Zenfone 3 ella kittum..
My suggestion would be to repair your phone and use it until some offers on Flipkart or Amazon.. exchange your phone then..