In an API call to add a new item to an existing order, honour the prices provided

Calls to

/api/Order/{id}/Items

use

Toolkit.DataClasses.Orders.API.NewOrderItem

which includes

-- UnitPrice (number, optional),

-- UnitPriceVat (number, optional),

-- Discount (number, optional)

but in all my tests these values are ignored and the item is added at its default value.