I had a battery replaced on a 6s here for $29. I highly recommend getting an appointment. Even with an appointment it will take several hours to get your phone back. Without an appointment they will tell you 4-5 days.
They can replace the battery. It wouldn't be cheap. For something like that, I would definitely recommend an appointment. There are other places that could do it for cheaper as well as quicker. Bad Apple is a good place to try.
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