If you know the IP address that they are coming from then you can block them from visiting your site very simply using the Insight Hosting Online Control Panel Control Panel. Simply log into your Control Panel and select 'Web Tools'. From the next menu select 'IP Address Blocking'.

To block an IP address simply enter the address into the input box in the format x.x.x.x and click 'Update Now'. This feature does support blocking ranges in the format x.x.x.x/xx - this is an advanced feature and should only be used in extreme circumstances.

To delete a previously blocked IP simply tick the box next to the IP and click 'Update Now'.