If you get fed up trying to collect cash, and anyway if you object to the context in which your work has been pirated, then you want it removed from the internet.
This is where the contact details for the company that owns the web host come in handy - see Locating website owners. In the US and EU at least, you can contact them to demand that they get their customer to remove your work. If their customer does not respond, the hosting company may and should remove the entire site.
Letters to hosting companies in the US should state that they are a takedown notice under the Digital Millennium Copyright Act.
Letters to hosting companies in the EU may refer to their country's implementation of the "Directive on the harmonisation of Certain Aspects of Copyright and Related Rights in the Information Society (2001/29/EC)".
In the UK that would involve pointing out to the internet service provider - the hosting company - that Section 27 of "Statutory Instrument 2003 No. 2498 - The Copyright and Related Rights Regulations 2003" allows you to seek an injunction against them to remove your work. Section 26 of the same Instrument specifies that they are committing a criminal offence - though we are not aware of any precedent-setting cases determining how this applies in the UK's "common law" system.
Local authority Trading Standards officers are now responsible for enforcing this law and you may be lucky in finding one who is interested in exploring this relatively new power as an alternative to tedious cases of short measure on market stalls.
The National Union of Journalists must not, can not and would not wish to dictate rates or terms of engagement to members or to editors. The information presented here is for guidance and as an aid to equitable negotiation only.
Suggestions apply to contracts governed by UK law only. In any event, nothing here should be construed as legal advice.