When printing a Crystal report through Service Desk the default paper size is 'Letter'. In the UK and Europe, the default paper size for printers is usually 'A4' so the reports don't print in the correct size.
When a new report is created in Crystal, the default paper size is set to Letter, it is this setting and not the machines preference that is used when the printing commences.
Open the report in Crystal and change the default printer settings. To do this, go to File > Page Setup... in the dialogue that opens, change the Size dropdown from Letter to A4.
A copy of the standard Incident report with this change made has been attached. If you use other reports or a custom version of Incident.rpt then you will need to make the changes to those individual reports following the instructions above.