Flipkart — Flipkart smart upgrade error "sorry abb not enabled on your account "

Last year October purchased Samsung Galaxy 20+ on Smart Exchange Offer, now I'm eligible for Buy back option trying to upgrade with new mobile, it's showing error as " ABB is not enabled in your device" regarding this i called customer care, no one is not resolved issue. More over they are saying pay balance advance amount and Keep with you.
Then why should we go for smart upgrade??
Seriously Flipkart is cheating and playing with Customers money.
My Account Registered No: [protected]
Reach me on [protected]
order id ending with :xxx9000
Below link many of them raised complaint on this same issue:https://www.consumercomplaints.in/?search=abb+is+not+enabled