Your options are pretty much rotobrushing, or reshooting. You might be able to do a little with the foreground using Keylight’s controls, but I can’t imagine it would end up usable. (And I’ve fixed some very poorly lit, rushed green screen footage before!)
On the shoot day, she should have been sent out to get a new shirt, directed to wear a jacket, or swapped to a blue screen if possible. There’s really no quick way to come back from this. Your best option is to reshoot and do it right, before getting to the edit suite.