Try updating waue_bookNow_1.php line 15 from:
$WA_MailObject = WAUE_Definition("mail.hsautorental.com","26","","","","");
to:
$WA_MailObject = WAUE_Definition("","","","","","");
Usually the email server and port settings are set on the server and default to the correct values. More often than not entering a value can cause issues.