Dual shock 4 issues with battery or the controller?

I'm having issues with my ds4 (had it since ps4 release) that I don't know if I need to replace the whole thing or just the battery. It charges really hot and barely holds a charge, so my first thought was the battery is dieing but its doing other weird things now. I left it charging on a non fast charge plug for a while and when I unplug it the controller still lights up orange slowly like its charging, I turned on the ps4 and that also shows the controller is charging even though it is not plugged in.

Anyone had a similar issue and know if it is just a battery issue or controller issue.

Also does anyone know any good replacement battery's (uk).

Thanks.