Oy vey. It seems like you're using many strategies at once, so I'm not sure what results I'd expect. For me, this kind of conversation needs to take place in-person, and needs to be framed as a "yes I'll do it, but..." not a "no I won't do it unless..."

I think, big picture, if you want to salvage this client (who seems to be moving on) you might wanna just get in the same room as them and start saying yes a lot. And you want to have this conversation last, after they're already super excited about the project and ready to get started.