@NicolasRaoul shame that they don't care as that's a flat PCI breach, but realistically there's probably not a lot you can do. You might be able to report it to your data protection commisioner (if the country you're in has such a thing
ico.org.uk is the UK one) or tweet about it which sometimes has an impact but past that apart from avoiding using that company, probably not a lot you could do.