Tuffnells have a limit of 9 digits to be displayed on shipping labels in the 'Consignment Ref' field. In the case that a consignment number is longer than 9 digits, Shiptheory automatically displays the last 9 digits of the consignment number.
If you would instead like the first 9 digits to be displayed, then navigate to the 'Advanced Settings' section of your Tuffnells settings. Scroll down until you see an option marked 'Shipping Label Consignment Number'. This setting will allow you to chose whether you want to use the first or last 9 digits of your consignment number on your Tuffnells labels.
If you have any queries or questions about this, please let contact support and we'll be happy to help!