....short and simple: grow!
The dude ripped you off and your worried about cutting ties?
....was he worried when he ripped you off?
I don't own a scale either, so when someone calls me to tell me that I shorted them, if not the same day then the very latest is the next day I will meet up and sq up.
More then likely he is buying a bag and thumbing a few grams for himself.
and that's kool as long as he told you before hand and you agreed.
Find a gangster, I'm 100% sure he can hook you up with nickles and dime bags.