It is all hearsay, no solid DPs whatsoever.

On the other hand some of us got lucky and got the full refund of the annual fee upon cancellation. I actually read on other site about someone got a $900 check after his account shown a negative $900 with those in and out AF posting and reversals. Then the credit balance was refunded. Though the more common ones were the $450 check, reported on the aforementioned thread.
By no means such were retention offers. Rather, some system glitches plus phone rep errors have generated some unexpected outcomes.