
Yep. That happened to me all the time when I was still actively working in the academic writing field as a member of the Academia Research writers pool. We all seemed to suffer the same fate.
Needing to revise the essay after the revision deadline had already expired based upon "QAD requirements". Which, I later learned, was their way of saying "We want to resell this paper. If you do not comply then, remember the penalty we did not charge you on this paper when you first submitted it ?
We will charge you that penalty and then some now." It sucks but that is how life at that company went on.
You had to be willing to revise the paper without any extra payment because doing so would be detrimental to the current income that you have in the "bank". I had situations were the company was demanding revisions for papers I had written 6 months, one or two years before.
No amount of explaining to them that I did not consider the "QAD request" a valid revision request unless I was paid for it convinced them to just let the old paper be.
I paid stiff penalties for trying to fight the system but that's another story.