Problems with nested type

[dyxenator]

I'm trying to generate a soap request with a nested type. SOAP UI generate this request:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:dept="http://atoss.com/ses/services/masterdata/dept-1.0" xmlns:typ="http://atoss.com/ses/services/masterdata/types-1.0">
   <soapenv:Header/>
   <soapenv:Body>
      <dept:GetDeptListRequest>
         <typ:Credentials>
            <typ:Logonid>xx</typ:Logonid>
            <typ:Clientno>xx</typ:Clientno>
            <typ:Password>xxx</typ:Password>
         </typ:Credentials>
      </dept:GetDeptListRequest>
   </soapenv:Body>
</soapenv:Envelope>

My code:

    factory = client.type_factory('ns1')
    credentials = factory.CredentialsType(
        Logonid=USER,
        Password=PWD,
        Clientno=CLIENTNO
    )
    request_data = factory.ListServiceRequest(
        Credentials = credentials,
        Filter = None,
        SelectedFields= None
    )

generates the following request:

<?xml version='1.0' encoding='utf-8'?>
<soap-env:Envelope xmlns:soap-env="http://schemas.xmlsoap.org/soap/envelope/">
 <soap-env:Body>
  <ns0:GetDeptListRequest xmlns:ns0="http://atoss.com/ses/services/masterdata/dept-1.0">
   <ns1:Credentials xmlns:ns1="http://atoss.com/ses/services/masterdata/types-1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="ns1:ListServiceRequest">
   <ns1:Credentials>
    <ns1:Logonid>xxx</ns1:Logonid>
    <ns1:Clientno>xxx</ns1:Clientno>
    <ns1:Password>xxx</ns1:Password>
   </ns1:Credentials>
   </ns1:Credentials> 
  </ns0:GetDeptListRequest>
 </soap-env:Body>
</soap-env:Envelope>

Notice the duplicate Credentials tags.

Also notice that the first Credentials open tag has the type ListServiceRequest !?!?

<ns1:Credentials xmlns:ns1="bla" xmlns:xsi="bla" xsi:type="ns1:ListServiceRequest">

Excerpt from dumped WSDL:
ns1:CredentialsType(Logonid: xsd:string, AbsentEmplno: xsd:string, Clientno: xsd:string, Password: xsd:string, uuid: xsd:string, pin: xsd:string)
ns1:ListServiceRequest(Credentials: ns1:CredentialsType, Filter: {[FilterCriteria: {FieldName: xsd:string, FieldValue: xsd:string}]}, SelectedFields: {[FieldName: xsd:string], selectionType: ns1:selectionType})

What am I doing wrong ? Is this a bug ?

[dyxenator]

WSDL attached.
dept.wsdl.txt

Excerpts from the WSDL

<xs:element xmlns:xs="http://www.w3.org/2001/XMLSchema" name="GetDeptListRequest">
  <xs:complexType xmlns:xs="http://www.w3.org/2001/XMLSchema">
   <xs:complexContent xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:extension xmlns:xs="http://www.w3.org/2001/XMLSchema" base="wstypes:ListServiceRequest"/>
   </xs:complexContent>
 </xs:complexType>
</xs:element>

<xs:complexType xmlns:xs="http://www.w3.org/2001/XMLSchema" name="CredentialsType">
 <xs:sequence xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element xmlns:xs="http://www.w3.org/2001/XMLSchema" name="Logonid" type="xs:string"/>
  <xs:element xmlns:xs="http://www.w3.org/2001/XMLSchema" minOccurs="0" name="AbsentEmplno" type="xs:string"/>
  <xs:element xmlns:xs="http://www.w3.org/2001/XMLSchema" name="Clientno" type="xs:string"/>
  <xs:element xmlns:xs="http://www.w3.org/2001/XMLSchema" minOccurs="0" name="Password" type="xs:string"/>
  <xs:element xmlns:xs="http://www.w3.org/2001/XMLSchema" minOccurs="0" name="uuid" type="xs:string"/>
  <xs:element xmlns:xs="http://www.w3.org/2001/XMLSchema" minOccurs="0" name="pin" type="xs:string"/>
 </xs:sequence>
</xs:complexType>

...

<xs:complexType xmlns:xs="http://www.w3.org/2001/XMLSchema" name="ListServiceRequest">
 <xs:sequence xmlns:xs="http://www.w3.org/2001/XMLSchema"> 
  <xs:element xmlns:xs="http://www.w3.org/2001/XMLSchema" minOccurs="0" name="Credentials" type="ws:CredentialsType"/>
  <xs:element xmlns:xs="http://www.w3.org/2001/XMLSchema" minOccurs="0" name="Filter">
   <xs:complexType xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:sequence xmlns:xs="http://www.w3.org/2001/XMLSchema" maxOccurs="unbounded">
     <xs:element xmlns:xs="http://www.w3.org/2001/XMLSchema" name="FilterCriteria">
      <xs:complexType xmlns:xs="http://www.w3.org/2001/XMLSchema">
       <xs:sequence xmlns:xs="http://www.w3.org/2001/XMLSchema">
        <xs:element xmlns:xs="http://www.w3.org/2001/XMLSchema" name="FieldName" type="xs:string"/>
        <xs:element xmlns:xs="http://www.w3.org/2001/XMLSchema" name="FieldValue" type="xs:string"/>
       </xs:sequence>
      </xs:complexType>
     </xs:element>
    </xs:sequence>
   </xs:complexType>
  </xs:element>
  <xs:element xmlns:xs="http://www.w3.org/2001/XMLSchema" minOccurs="0" name="SelectedFields">
    <xs:complexType xmlns:xs="http://www.w3.org/2001/XMLSchema">
     <xs:sequence xmlns:xs="http://www.w3.org/2001/XMLSchema" maxOccurs="unbounded">
      <xs:element xmlns:xs="http://www.w3.org/2001/XMLSchema" name="FieldName" type="xs:string"/>
     </xs:sequence>
     <xs:attribute xmlns:xs="http://www.w3.org/2001/XMLSchema" default="exclude" name="selectionType" use="optional">
      <xs:simpleType xmlns:xs="http://www.w3.org/2001/XMLSchema">
       <xs:restriction xmlns:xs="http://www.w3.org/2001/XMLSchema" base="xs:string">
        <xs:enumeration xmlns:xs="http://www.w3.org/2001/XMLSchema" value="include"/>
        <xs:enumeration xmlns:xs="http://www.w3.org/2001/XMLSchema" value="exclude"/>
       </xs:restriction>
      </xs:simpleType>
     </xs:attribute>
   </xs:complexType>
  </xs:element>
 </xs:sequence>
</xs:complexType>
...

[dyxenator]

Could it be that zeep incorrectly handles GetDeptListRequest being an extension of ListServiceRequest ?