Battery indicator showing wrong

[Pp04]

Hi 

I have been facing a few issues with my Xperia c5 ultra dual lately.

Other things seems to have corrected themselves with some help from support here. But there is one thing, I think that the battery indicator of my phone is not showing correct percentage of charge. 

Sometimes it s stuck at a number for a long time ( especially when it is fully charged or even it not fully charged has been just removed from charging ) and other times just slides down real fast( especially when it reaches lower level)

At other times it takes a lot of time charging .

Is there a way I can correct it my self 

[Quickwitted]

Same unit. Same problem. Sony please reply here.