Error codes and unable to connect to AVG server

I am reverting from the trial period which has expired to the AVG free edition. I have followed the instructions given in 'how to' and now I keep getting the error code 0xe0018d0d and told to contact the service centre. I've restarted several times but still get the errors!! How to fix please?

Hello Nigel,
We regret for the inconvenience caused to you. We understand that you are trying to uninstall a trail version of AVG and install a free version.  We would request you to run the AVG remover tool to remove all the remnants of the failed installation as described below.
To run remover tool, please visit http://www.avg.com/tools#tba2 and click on "AVG Remover" to download the remover tool and run it on your PC. It will ask you to select which product you would like to uninstall. Please select all AVG products detected and follow the setup instructions to uninstall AVG. Once the tool is run, your PC will automatically reboots. After the restart, please check if a folder with name AVG Remover is created under C:\ and remove it.