In a letter to the Senate Commerce Committee chairman, Apple has hinted at possibly offering a rebate to customers who bought replacement batteries at full price because of the "Batterygate" controversy. Apple reduced battery prices from $79 to $29 in an attempt to appease users who saw an iOS update throttle their devices. Users were not notified beforehand that the software would slow down performance.
https://www.notebookcheck.net/Apple-may-offer-battery-rebate-in-regard-to-Batterygate-controversy.281660.0.html