If you have c-panel (or something similar) on your host, you can fix the problem yourself by adding a redirect from www.tankuniversal.com to tankuniversal.com.
Only if the Cpanel server also controls your DNS in addition to the website itself -- if it's a 3rd party DNS server than cpanel won't be able to fix it. The visitor would never make it to the webserver to be re-directed in the first place.