Thinkpad Battery Issue

Salam I own a Thinkpad P14S Gen3. Bought it last yr in used. Its battery is officially covered in warranty still (in UK). The issue is, battery suddenly goes from 30% to 6% and laptop switches off if not plugged in at that time. So i guess, i need to change battery. The question: ❓ Where do i get reliable battery for my Thinkpad? In Islamabad / Rawalpindi/ Lahore