I presume the poster could use EU data protection / privacy law here? Companies are legally required to keep personal data accurately, and if you tell them that

I presume the poster could use EU data protection / privacy law here? Companies are legally required to keep personal data accurately, and if you tell them that the data they hold on you is incorrect, they are required to correct it. A simple formal letter / email to them saying "My address / country of residence is X" should be all that's legally required. You may need to contact your local Data Protection / Information Commissioner to get them to enforce it. If their systems can't handle it, then storing personal data in that system is illegal. :)