The big delay comes after Apple (AAPL) acknowledged intentionally throttling the performance of some iPhones in order to prevent those smartphones from abruptly turning off because of elderly batteries. In an effort to make nice with angry customers, the company recently dropped the price of replacement batteries for certain iPhone models to $29 from $79.

The affected iPhone models include the iPhone 6, iPhone 6 Plus, iPhone 6s, iPhone 6s Plus, iPhone SE, iPhone 7 and the iPhone 7 Plus. Apple said it would eventually fix the battery problem in recently released iPhone 8 and iPhone X models through an iOS update this year.

When Washington Post columnist Geoffrey Fowler tried to upgrade his iPhone’s battery, he wrote that “thousands of other customers” were already ahead of him, and he would have to join a “weeks-long waiting list.” Fowler added through a post on Twitter that an Apple Genius bar worker predicted that Apple’s “battery stock levels may not be back to normal until summer.”

Fortune contacted Apple for comment and will update this story if it responds.

https://twitter.com/geoffreyfowler/status/948967546182549504

Other Apple iPhone customers eager for the battery upgrades also reported similar stories on Twitter on Thursday.

https://twitter.com/dickweit45/status/948684502469095424

https://twitter.com/chey_cobb/status/948992735943344128

This is the Apple store line in Sacramento for Genius Bar appointments for iPhone battery replacement. Swing and a miss, Apple. pic.twitter.com/I0MjnYPL1a

— Tracie Cone (@Tracie_Cone) January 2, 2018

https://twitter.com/RobertT18542781/status/948992634013433856

https://twitter.com/thebrianung/status/948991003805044736

https://twitter.com/mdsbarry/status/949002406662213632

Made my appointment at an Apple Store a week ago to get a replacement battery for my iPhone. They are out of batteries. O-U-T. OUT. You have to be kidding me. #apple #iphone #customerservice #fail #applestore #estero #fl

— Maribeth Doran (@mdmv) January 4, 2018

The moral of the story is that if you want to get a new iPhone battery, be prepared for a long wait. You’ll have to schedule an appointment at your nearest Apple Genius Bar, visit the store to talk to a representative about the battery problem, and then join a waiting list.

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Apple says on its website that mailing your iPhone directly to the company for a battery replacement could lead to a waiting time of “5-9 business days” before you get your phone back. However, it’s unclear how many people are mailing their iPhones and whether that could lead to longer waiting times, like is in the case in Apple stores.