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 'turn on' after a few seconds 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
https://www.cloudzy.com/resize-windows-vps-drive-partition-without-losing-data/
If you had any issues then please open a ticket as sometimes because of resources limitation the upgrade does not goes through.