Since early November, a growing number of iPhone 6s owners around the world have been complaining about their phones shutting down unexpectedly, even when there was significant charge left according to the phone’s battery indicator. Apple admitted that some of the phones needed to have their batteries replaced, and offered to do the work for free.

The company also said that anyone who had already paid to have the problem repaired could apply for a refund.

But a week after Apple announced the repair program, a number of questions remain. And the company hasn't made it easy for consumers to find out whether their phone is eligible for the fix.

Only a "small number" of iPhone 6s units are affected, according to the company: those manufactured in September and October 2015, with a precise range of serial numbers. The company’s website invites iPhone 6s customers to bring their phones to an Apple Store or an authorized Apple service provider, or to call Apple’s tech support, for details. (Cellular carriers aren't participating in the repair program.)

However, Apple hasn't told consumers which serial numbers to look for, or provided any other method for determining whether a particular iPhone 6s is affected. And if you're hoping to get the information by phone to avoid your local Apple store during the holiday-season crush, you're likely to be disappointed.

We called tech support at about a half-dozen Apple stores in the New York City metropolitan area, including the region's flagship store on Fifth Avenue in Manhattan, posing as a customer seeking information.

In most cases, a recording told us to try again later due to high caller volume—and then it hung up.

But even when we did get through to a live person, the exercise proved to be fruitless. For instance, a tech specialist at Apple’s Fifth Avenue store asked us to go into the phone's General Settings menu, then open the About section and read her the serial and International Mobile Equipment Identity (IMEI) numbers—but then refused to say whether the phone came from one of the affected batches. She insisted that we bring it in for an evaluation.

We had similar experiences with other salespeople and technicians, who told us they'd been instructed not to provide the information to consumers over the phone.

Earlier this week, the website 9to5mac.com published a list of what it says are telltale digits in affected phones' serial numbers, but Apple declined a Consumer Reports request to comment on whether that information is accurate.

The company also declined to tell us whether there is an adequate supply of replacement batteries available, how many phones were affected, what caused the problem, or whether the same batteries were used in other iPhone models. 

By the way, this isn't the only iPhone battery problem in the news. Owners of several iPhone models have been complaining that batteries were draining rapidly on phones that were updated to the most recent version of the operating system, iOS 10.1.1. Apple hasn't said when that problem might be fixed.

If your iPhone 6s is giving you trouble, here is our advice for minimizing the hassles involved in getting it fixed.

  • If you want to get on the phone with an Apple store in your area, tell the robotic voice that answers that you want to speak to a human, and when it prompts you for more details, say “buy an iPhone.” Apple is more likely to connect you with a real person if it thinks you're looking to spend money.

  • If you’re confident that your iPhone qualifies for service, try to make sure the store has the parts available before you bring the phone in. But don’t be surprised if the salespeople or technicians won’t provide that answer. One Apple support person said that if she told us a battery was available, and “someone who came in before you took the last part, you’d think we lied to you.”

  • Since you can bring the phone to any Apple store, not just the one where you bought it, consider going to a store in a less populated area since this is such a busy shopping season.

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