Flipkart — fake 90 days buy back guarantee

Address:

14-136 2nd Floor Bommidi Building Beside Reliance Bunk Road Near Rtc Complex, East Godavari, Andhra Pradesh, 533103

Two months back i brought nubia red magic 3 from flipkart with 90 days buyback guarantee... Now i am trying to exchange my mobile... But flipkart not listed my mobile in exchange program not even nubia brand names also not listed. Only one month remaining to exchange... I contacted flipkart customers care to resolve problem almost one week completed.. Till now problem not resolved.
I never thought, such a reputed company. Giving fake buyback 90 day 90% guarantee. To increase their product sales...