According to the CyberSource API docs (http://apps.cybersource.com/library/documentation/dev_guides/CC_Svcs_SO_API/html/wwhelp/wwhimpl/js/html/wwhelp.htm#href=reply_fields_so.html) a field called ccCaptureReply_processorTransactionID should be returned:
ccCaptureReply_processorTransactionID
Processor transaction ID. This value identifies the transaction on a host system. This value is supported only for Moneris. It contains this information:
However in the .NET SDK this property does not exist. Does the service reference in the SDK and the nuget package need updating?