Cannot find an UpdateCustomer information function in the EWAY Rapid API

Question

Using the EWay Rapid API .NET SDK and cannot find anything in their documentation for how to go about updating customer information (i.e. name, contact details etc).

We are using the Responsive Shared Page connection, capturing payment on the Eway platform. We are setting the SaveCustomer property to return a CustomerToken which we store to reuse at a later time.

I've noticed that when creating a new Transaction for the customer, if we pass in new customer information (i.e. change their name), it ignores the Token we supply and instead creates a new Customer inside of eway.

The RapidClient library defines the following:

    //
    // Summary:
    //     This Method is used to update a token customer for the merchant in their eWAY
    //     account.
    //
    // Parameters:
    //   paymentMethod:
    //     Describes where the card details will be coming from that will be saved with
    //     the new token customer (Direct, Responsive Shared, Transparent Redirect etc).
    //
    //   customer:
    //     Request containing the Customer details
    //
    // Returns:
    //     CreateCustomerResponse
    CreateCustomerResponse UpdateCustomer(PaymentMethod paymentMethod, Customer customer);

It requires a paymentMethod be passed in, and seems the point of the function is to update this. I tried passing in all of the valid values for this, and then passed in a Customer record which contains the updated information (change spelling of the firstname).

That does not update it, instead, it returns the error code: V6047 which means missing RedirectURL (at least for shared page mode).

Am I completely missing something obvious? If I can't edit the customer card during a transaction, how can I not have any option to update their contact details somewhere else?

EDIT: To clarify I'm using the .NET Framework version of their SDK which is 1.6.3. I'm not sure if this has been depreciated as the documentation looks to focus more on the .NET standard. I note that the library I'm using also references the same documentation.