If you have a trademark on the domain, you can file a complaint with the Domain Resolution Service. They'll look at the trademarks and if they deem you to be the valid owner for the domain, will transfer the domain to you.
Thanks for the answer. Just to clarify, we do not have a trademark on the domain, but only on the company name i.e. on "our_company_name" and not "our_company_name.com". I assume we need a lawyer to file a proper complaint. Do you have any experience in how much the whole process costs?