If the file you downloaded has the extension 'Undefined', you can manually rename the file to the correct '.pfx'. You can do this as follows;
- Right click on the certificate
- Click on 'Change Name' or 'Edit Name'
- Change the text 'Undefined', to '.pfx'.
- Confirm the change if you are prompted to do so.
You should not request the certificate again. This will result in additional costs.
Have you started a new request anyway? Then contact the Service Desk.