The service client component is the component that you would need to use for handling web service calls through your Robotic automation
If the input complex type resides within the schema of your wsdl, you should be able to find the complex type in the list of properties once you extract the proxy of that type within your automation.
If the complex type does not reside within the schema of your wsdl, you will need to use a script component to handle creating an instance of the complex type to pass into the service client functions. The same goes for output as well.
The service client component only consumes and outputs simple types by default.
Another option would also be to create a custom service client component yourself and adding the component to your automation.
Below is a blog that goes into creating a web service component through c#.