Amazon/Flipkart phone exchange?

What’s been your experience with Amazon and Flipkart’s phone exchange checks during deliveries. Planning to upgrade my phone and dreading the exchange check because the delivery people are known to be scammy. Two years ago when I got my current phone the delivery guy slashed my exchange value in half after the stupid checking app misdiagnosed my phone left and right. What’s been your experiences off late with these apps? Might try to sell on OLX instead before i go ahead.