Amazon India — purchase made

I placed an order for mobile with exchange, however due to unforseen reasons, i am not able to return my old mobile. I requested them to charge mere 1500 they offered for exchage n they ask me to cancel whole order n place new one. Cce was also very sarcastic. Very disappointed with this. Is it so complicated for them to take this charge n cntinue my order shpment. Even the managr who spoke wasnt helpful