Government agencies don't really chase the airlines either. There might be one or two countries that do, but I couldn't tell you which ones and whether they would accept your claim.

Most people make their claim through a specialist law firm found on the internet, in the process handing over much of what they are due.

Vueling basically will not pay without a court order. Everything in their process is designed to make you give up and go away in frustration. (until they are again the cheapest option for a flight you need and you hold your nose and book with them...)