Amazon India — (I can Return But I amForced to Keep a Product having Lesser Size as the Product Price has increased)

Last Day I brought a Nike Backpack Which Claimed 30L volume.When it came the Specification written on the bag was 16L.I thought it was a seller mistake.Then Exchanged it.Boom! Again i got the same product of 16L.So when i complained to customer care they said that i can return and take refund.But i couldnt as the price for bags have increased and Its now almost triple of what i brought it for.The Customer Service was Changing each person one after another till a 3rd person told me only refund is possible.Actuay what is this?I feel this is cheating.16L is very small but I think i should get a 30L backpack from amazon.Either i need a compensation for this time loss or another 30L nike bag or the money to buy it.I need any of this It is just ridiculous.I hope amazon resolves me by giving me either a 30L Nike backpack or giving some amount as compensation as they cheated me.Also I took Prime as there was 200CB as amazon pay.Now they deny there was no offer like that.This offer made me choose prime and now its like this.They also didnt gimme flat 50 on 500 for upi payments.They are just doing gimmikky stuff to earn money and customers to sell.Please Amazon i can attach proofs all day long