Apple’s discounted program lets iPhone 6/6s/SE owners replace their device’s battery for just $29 (limited to one repair per iPhone) instead of $79, regardless of its condition, but iPhone 6 Plus owners looking to take advantage of the lower fee will need to wait a few months.

An internal document distributed to Apple’s retail stores and Authorized Service Providers this week, seen by MacRumors, acknowledges that iPhone 6 Plus replacement batteries are in short supply and won’t be available until late March to early April in the US and other regions.

The company wrote in internal documentation that lead times may vary in some regions, including the Middle East, Africa, Latin America, Russia and Turkey.

But what about batteries for other models?

From the article:

Apple’s internal document quotes a shorter wait of approximately two weeks for iPhone 6 and iPhone 6s Plus battery replacements and adds that batteries for all other models like iPhone 6s, iPhone 7, iPhone 7 Plus and iPhone SE are expected to be available without extended delays in most countries.

A reliable source at an Apple Authorized Service Provider indicated that they recently received a package with dozens of replacement batteries, the majority of which were for iPhone 7 and iPhone 7 Plus models.

Because availability of iPhone batteries varies by location, call your local Apple store before bringing in your device for a battery replacement service. Another option: check with your favorite Authorized Service Provider to see if they have spare batteries in stock.

Apple’s battery replacement fee will return to its normal level ($79) on December 31, 2018.