I have upgraded but I do not see any results? If that is the case then please follow the steps below:
Please pay any unpaid invoice (if there is any) then you need to do a 'hard' reboot from your VPS control panel. Simply please go to the control panel and click on 'turn off' and then click on after a few seconds 'turn on' again. Now you should see the upgrade changes.
In some cases, you have to increase the hard drive storage. In order to do that please check out
If you had any issues then please open a ticket as sometimes because of resources limitation the upgrade does not goes through.