Hello I understand the situation, as @Rikafip suggested you can export this chat history or keep that images and screenshot of those admin and team from digitalbits.

Also just a suggestion when you posted an image make sure you adjust the width and height so it would not cover all over the screen. Its too big and eating my screen 

To do that:

---

Based on their words I doubt they will pay whats on the spreadsheet. OP can make a flag type for this they imposing they will never pay you guys. This is a legendary tactics of a legit fraudster who will just make some free advertisement. Thats why the manager of a campaign should come from an external source cause its from their team, who knows that this could end up badly like this.