See the following from iPhone Battery & Power - Official Apple Support
Send in for repair
Start online or give us a call. We'll send a box right away to collect your iPhone. You can then arrange to ship it to an Apple Repair Center at your convenience. We'll deliver your iPhone back to you in 3-5 business days. If you have AppleCare+, you can also use our Express Replacement Service
More information on Express Replacement:
iPhone Express Replacement - Apple Support