Once you make a deal with someone, It's really important to carry it through. You start developing a wrong reputation, it makes it impossible to make future deals. Once you shakes hand, that should be it.
You always got to stand up for yourself, you just have to FIGHT for yourself, basically nobody else is gonna FIGHT up for you.
You didn't fight for yourself, and therefore you're fired!
Never beg when you try to sell something.