Hello,
Welcome to the forums.
All customers have the ability to restart and manage their servers - it's not true that only admin can restart it.
To restart your server, please login at
http://streampanel.mixstream.net with the same login details that you registered with and there will be a link on the menu for your server (in your case it will say uks-vn:8032), click on that and you will see some links and buttons show up. Click on the Restart button and confirm - your server will then be restarted within about 20 seconds.
It's worth noting that you should only restart your server if you've made a configuration change - other than that, it will never need restarting.
I hope this helps!