About apple care plus

I bought an iPhone in Korea

While traveling in the U.S., I visited the Apple Store in the U.S. to receive a refurbishment due to damage to the rear camera, but the store "has no parts." And I got a reply saying, "Only products purchased in the U.S. can be refurbished in the store."

And I asked you to contact 1800 692 7753, but I'll see how to talk because my English is not good enough.

Is it impossible to refurbish or repair an iPhone purchased in Korea in the United States?