C# web application dynamically calling web services from 3rd party

my C# web application should call web services provided by 3rd parties. Which web service to call will only be known at run time when the provider is detected. For example:

Supplier #1 => client.ReceiveOrder(string orderNumber)

Supplier #2 => client.OrderReceiver(int OrderId)

Supplier #3 => client.GetOrderFromOutsideWorld(int OrderId, string OrderNumber)

So basically only after an order is received the application will know what client to call and what method(s) are exposed.

Any hints about how to realize this? Best practices to follow?

Thanks a lot in advance!