Amazon India — Refusal of return option and refund

We bought sofa cover from Amazon and it didn't fit our sofa. When we wanted to return, Amazon agreed to refund us. Later on they said they can't refund and it's not eligible for return
We even received an email saying we will a refund
The product is not damaged or defective. It's not fiting our sofa so why is not eligible for return is beyond my understanding