Amazon - Issue with Exchange delivery

I placed an order from Amazon for MI Note ** pro on **/*/**** through * months EMI and exchange of old phone for Rs ****. I used my Citibank card to make the transaction. The delivery executive came to my place the very next day at **:**am, carefully examined my phone and handed over the new phone and left.
He came back to my place at *pm and says my exchange device has display issues so he cannot take it. He then asks me to pay Rs **** but I say I have made the payment by credit card and do not have such money. I ask to speak to his manager, then I speak to someone by name Robin and he says I need to pay the amount. He then washes his hands off and asks me to speak the executive only. I even offer to give him the new device back as I didnt have so much money but he denies as the seal was already broken by me. My argument with the delivery executive continues for an hour and finally I agree to pay him Rs **** which is when he leaves.
My concern here is if my exchange phone had display issue he should have told it right away and not after *.* hrs. I could have atleast cancelled my order and placed one after a few days. But that didnt happen.
Moreover the transaction amount is not converted to EMI and I was charged full on my card. When I spoke to Amazon about this EMI issue they asked me to speak to my bank. My bank inturn asked me to speak to Amazon. I am having a run around here.
Are these the perks of being a loyal customer for around a decade and a Amazon Prime customer for * years.
My details are mentioned below:
Name: Kiran Kumar A
Phone: ********** (Registered with Amazon)
Email: Kiran_kumar******@yahoo.co.in