i think there is not find any free program for do this action...
you can buy whmcs,clientexec,modern bill 5 license about $15 up to $25..they are compelete management and etc.
i think you can connect to directadmin database and write that program manually.it should be easy.you can get user directadmin database password and username with run this command on ssh :
# cat /usr/local/directadmin/conf/mysql.conf | more
Bye