You have part of the picture, but here's what you are missing. Your former self, your past self and your future self are indeed separate beings, but these are all just physical manifestations of the same soul. Bad karma has a negative impact on the soul itself and it is your immortal soul that God is concerned with. Your spiritual self, not the physical you.
Correcting karma is but a small part of the reincarnation process however.
That's really just semantics; if all these selves are the physical manifestation of a soul, then that soul is not me, so again I am punished or rewarded for actions taken by one other than me. And that is a great injustice, a great evil
In other words, that soul is not mine, rather it is some soul common to many persons
Oh and an aside, you are wrong to think I only had part of the picture, all this I was already familiar with