Name change.
I did some work for a huge company, it was exactly as they requested (even against my advice that I thought they were missing the point). It was over a weeks work.
Was delivered to them they said thanks bla bla and I invoiced.
Now a month later I'm expecting payment and they are saying they were expecting more from me due to the track record of achievements I told them about at the begining of negotiations. But these achievements are averaged out across all of my work, I can't guarantee anything for a single peice.
They are asking for another one for free.
Aibu to refuse to do so, request payment ASAP and if not (on my social media) make a post where I talk honestly about what happened to me and by whom?