Agency not paying final invoice

[TheFaQQer]

My understanding is that once you are 'introduced' to a client, you cannot from that point onwards opt-out.

So, if you have physically met the client, and then opted-out afterwards. Tough to them.

However, IANAL and IANAA, etc...

WHS.

Once the client can identify you (which could even be once they receive your CV), then you cannot opt out, even if you wanted to.

You must opt out, in writing, before the client knows who you are.