Apple reportedly is considering offering a rebate to users who bought an iPhone replacement battery at $79. They had quickly dropped the price of replacement batteries to $29. Users who paid full price may now be eligible for a rebate.
The battery replacement was in response to reports Apple purposefully slowed down older model phones.
Nothing has been decided yet, but a rebate would be the right thing to do.
Source:
http://money.cnn.com/2018/02/06/technology/apple-iphone-rebate/index.html