Using Delphi web service with custom SOAP headers using WCF

Question

We need to use a third-party web service (written in Delphi) using WCF. The problem we are facing is that the Delphi service is RPC / Encoded and uses custom SOAP headers. If we add the following to our ServiceContract (to handle RPC encoding):

[XmlSerializerFormat(Style = OperationFormatStyle.Rpc, Use = OperationFormatUse.Encoded)] 

we get an error saying that this cannot be done in conjunction with MessageContracts with headers.

 Message *** must not have headers to be used in RPC encoded style 

Does anyone know about this?

thanks