Truenet Commerce — wrong product

Address:

Hyderabad, Andhra Pradesh, 500005

This time i was delivered a phone in good condition but the redmi note 5 pro phone was 4 gb ram whereas i paid for 6gb ram. I discovered this immediately after the delivery and called flipkart. They apologised and told me 'seller offers refund' saying 6gb is not in stock. I requested for the difference amount of 2k to be refunded.
I submitted my old moto g4 + as exchange during bb sale and not willing to live without any mobile.

I am surprised how seller truenet commerce is unwilling to take this option. I request you to either replace the current phone with 6gb or refund the difference amount (4gb ram redmi 5 pro costs 2k less than its 6gb counterpart)... Not full refund.
Thanks,
Prasad