Incidence of Cheating by FLIPKART

I placed an order to FLIPKART for a Redmi Note Pro 6 (Black, 64 GB) mobile phone amounting Rs. 12,999/- on 09-08-2019 and also mentioned delivery point at Main Hostel, Medical College, Kolkata in favour of my son Soumyadeep Roy. Online generated order number of the said item was OD116222769011847000.
On 12-08-2019 afternoon, my son received the parcel and found that instead of Redmi Note Pro 6, an ordinary Lenovo mobile has been sent. He immediately informed me and also discussed with the Ekart delivery man and according to his advice he made a phone call to the Customer care and he was ensured that the item would be changed on filing online ‘Return Form’. Due to non-availability of ‘Online RETURN’ button at that time corresponding to that item, I sent an e-mail immediately to Customer Care at 16.19 hrs on the same day along with photograph of received item. After wards, at night, I filled online ‘Return form' also.
On 15-08-2019 at 11.27 hrs, Mr. Mehar Taj, Customer Support of FLIPKART wrote to me that he would lodge an F.I.R. on receiving my consent and immediately after that at around 12.18 hrs, I confirmed him. But surprisingly he on 17th August 2019 at 12.29 hrs sent a shocking e-mail as follows:-
“Hello Tarak roy,
We are writing to you n continuation to your return request for Redmi Note 6 Pro (Black, 64 GB), Since we haven't got an email from you giving consent to the FIR being lodged within 48 hours, the seller will not be able to fulfill your return request. Due to this your return request has now been cancelled.
Regards,
Mehar Taj
Flipkart Customer Support “

After that I had sent several mails to Flipkart Customer Support as well as one mail to business@flipkart.com addressed to Chief Executive Officer, Flipkart but till date matter has not been resolved.