fetch UserInfo

Under the file /engine/Shopware/Bundle/AccountBundle/Service/StoreFrontCustomerGreetingService.php, there is fiunction  fetchUserInfo, which fetches the user info like firstname lastname etc. I would like to ge tthe user company name also here. It is in the “s_user_billingaddress” table. How can i extent the function in another file and make the necessary changes in query, so that the  original shopware file is kept intact and we work on  the extended file for this change