Apple may take another step to address the backlash over its decision to slow down older iPhones.

Apple told a U.S. senator it is “exploring” whether to offer a rebate to customers who paid full-price for a battery replacement, according to a letter released Tuesday.

The tech company apologized to customers in December for using a software update to slow the performance of older iPhone models. It also dropped the price of replacement batteries for the iPhone 6 and later models from $79 to $29.

Senator John Thune, the chairman of the Senate Commerce Committee, previously sent a letter to Apple with several followup questions, including whether customers who purchased batteries at full-price might be compensated.

“Apple has acknowledged that its initial disclosures came up short,” Thune said in a statement Tuesday. “Apple has also promised the committee some follow-up information, including an answer about additional steps it may take to address customers who purchased a new battery at full price.”

Apple has said the goal of the slowdown was to “smooth out” peak power demands and prevent older iPhones from sudden shutdowns as their lithium-ion batteries degrade. But it resulted in disappointing performance for users.

Slowdown backlash

The original disclosure set off a backlash among consumer groups and government authorities around the world. U.S. regulators have also begun probing Apple for information on the slowdown.

“While our intention has been to give our customers the best products and the best experiences, we have apologized to our customers and, as described here, have taken a number of steps to address the complaints,” Cynthia Hogan, Apple’s VP of public policy, wrote in the letter released Tuesday.

Hogan said Apple is “seeing strong demand” for the discounted battery replacements so far.

A decision to offer a rebate to customers could help offset some customer outrage, but it might also add to investor jitters about the cost of Apple’s strategy for defusing the bad PR.

On a conference call with analysts last week, Apple CEO Tim Cook was asked whether investors should worry about discounted battery replacements cutting into the number of customers who feel the need to upgrade their iPhones.

“We did not consider in any way, shape, or form, what it would do to upgrade rates. We did it because we thought it was the right thing to do for our customers,” Cook said on the call. “Sitting here today, I don’t know what effect it will have.”