Should your location be outside the area a provided link + has little use
you might try the wider range an additional area could provide here:
iPhone Battery Repair & Replacement - Apple Support
//support.apple.com/iphone/repair/battery-replacement
If no Apple repair centers or official Apple Stores are in your area,
then check to see who in your region may be an Apple Authorized
Service Provider. ~ And, if there's no one there to match that niche
look into a cellular services provider; or who repairs & sells iPhone.
Authorized repairs can appear as independent local businesses.
The linked article details cover wider range of global possibilities.