Flashstar Commerce, Flipkart — I am complaining about my infinix smart 4 plus order.

Address: Chattadangal, Mihijam, Jamtara, Jharkhand, 815354

Website: Flipkart

I bought a phone from Flipkart from the seller named Flashstar Commerce on 4th and I raised return and refund request and they told they will get back to me on the 10th. On the 10th they have messaged me and said the seller has rejected your return and refund. I don't know the reason behind this. I have provided all the asked documents but then also facing this.
I am a student of class 11 and I have my exam on the 13th that's why I have bought the phone but facing these difficulties.
I have placed a return request again and they told me to wait till the 13th.
Please help me sir/madam. It's my earnest request to you.