What happened is that most likely you got scammed, they sent you $1000 worth of BTC with low fees you released an escrow or paid something or sent your coins and then they simply replaced the unconfirmed transaction and they sent you $100 probably as cover up to claim in a dispute that's the amount you agreed on!
This should be what transpired. That's if OP was truthful with what they said happened. Otherwise, one would conclude that OP is just trolling since they haven't presented a simple thing as the TX ID to buttress their story.