PayTM - Replacement not provided

I ordered an Apple MacBook Air from Paytm on **th October ****. It was delivered to me on ** th but I returned it on **th oct as the product was defective. The replacement order was placed on **th October and was to be delivered by ** October but I haven't received the product yet.
I raised multiple complaints regarding this via different means viz- their messaging portal, their customer care and even email but the only thing they have to say is that team is trying to retrieve the product from the seller. They also gave me the number of the seller, but the seller is not responding. I asked them to refund my money as the seller is not responding but they keep iterating that this is a replacement order and we cannot cancel the order. Moreover the seller had a non- refundable clause but since the seller is not responding , logically the policy also becomes invalid.

I even asked them to connect me to any higher authority but they always make the excuse that seniors are busy in other calls and cannot talk.

They are neither giving me the product nor are they refunding my money. I am seriously fed up with their resolution process because it's redundant and pathetic. They don't even provide any contact detail of point of contacts . The customer care people say that all they can do is to raise complaints and also don't allow any conversation with higher authorities.

Some order related info -

Original order no - ********** (returned)

Replacement order no - ********** ( not yet delivered)