If someone already register domain name that matching your company name, nothing you can do because domain name  can be register by anyone and usually works first come first basis. You can register your company domain name with available domain. So, I would recommend, please get your domain name reserve. This way you can use your domain name in the future when your website is ready for public. About someone using your company name is not that clear question, so please contact us, we may be able to help you. Thank you.