If you own a 2016 or 2013 13″ MacBook Pro (non Touch Bar) and your battery has expanded, Apple will replace the battery free of charge as part of their 13-inch MacBook Pro (non Touch Bar) Battery Replacement Program, launched this past April.
Eligible MacBook Pros can be determined by entering its serial number on Apple’s support page. You may then take the MacBook to an Apple Retail Store, Apple Authorized Service Provider, or you can mail the MacBook to Apple’s Repair Center. Apple states that service may take 3-5 days.
This service is only for 13″ MacBook Pros without a Touch Bar. According to Apple, “Apple has determined that, in a limited number of 13-inch MacBook Pro (non Touch Bar) units, a component may fail causing the built-in battery to expand. This is not a safety issue and Apple will replace eligible batteries, free of charge. Affected units were manufactured between October 2016 and October 2017 and eligibility is determined by the product serial number.”
For more information, see Apple’s 13-inch MacBook Pro (non Touch Bar) Battery Replacement Program page.