Is your iPhone 6s charger not working as fast as it used to? If so it will be better to repair it for better charging. Plenty of way iPhone charging port could damage or fail to working capability. if your phone not able to hold the charge then battery be slow and performance of iPhone will not better. So replace it in the reliable place. Our experts are capable to figure out your problem and it might be an easy fix to theirs. They are much trained on this specific issues and maintain their task accurately.