Help S3 Charging issue

[S3 Charging issue]

Hi there. I have had my S3 for about one year now. It now loses charge while plugged in to the charger! And when I remove it from charge it starts dying rapidly if I am using it. If i leave it on charge over night with all the networks switched off it only goes up to about 35-40% battery sometimes only in the 20s. I have tried many different cables and bought 3 new chargers. I have even tried 3 new batterys (2 official and one not). Nothing seems to be solving the problem. I even tried to clean the pocket fluff out of the micro usb port and no change! Any idea what I can do/what this could be. Is this phone a write off?

 

[El Presidente]

Given the symptoms, I doubt it, but check your battery usage screen, is there any specific app that's eating in to battery?

If yes, uninstall that app.

You could also try a factory reset, but from what you've said and tried so far, I think you'll need to call it in for a warranty replacement (if you're still in the warranty period).