I know it's your first post and all, but don't be so dramatic! No one has cheated you out of anything...

If you want to insist someone has cheated you, well, you cheated yourself because you failed to be aware of the policies for the FFP you enrolled in, including retroactive claims for mileage.

So now you know where to claim for miles retroactively.

Also, another point you obviously weren't aware of...you may have passed security, but if there's an issue with your boarding pass, you can usually get it fixed at the gate with the agent there.