Ensure you have a 'proper agreement'.
Ask for "your money" [politely] NOW !
Point out [politely] that they should you pay within NNN days, from "NOW".
Point out [politely] that if they don't pay you "NOW" that they might be subject to 'penalties' [be vague ?]...
Since the anonymous 'accounts' are often dealt with by someone who is quite different from the guys you initially had dealings with, then c/c those guys... They might have a conscience ? ...
If all else fails appeal to those guys' 'better nature'... if they have one...
If 'all else' fails sue them !!! ...
We are all in the same s**t ! We can only hope that 'they' see that they can't stop the "wheel going round" and then continue on as they are.....
Rant over. π