Ignoring Xsd Squence Order on Serialization in .NET

I am consuming a 3rd-party webservice (of which, I have no control over) in .NET.

I noticed some of my properties were not being set when the response was returning and being serialized from the service.

I have noticed something strange with their response though.

Ths is a sample of their WSDL

<xs:complexType name="letters">
    <xs:complexContent>
        <xs:extension base="tns:response">
            <xs:sequence>
                <xs:element name="a" type="xs:long" />
                <xs:element minOccurs="0" name="b" type="xs:dateTime" />
                <xs:element maxOccurs="unbounded" minOccurs="0" name="c" nillable="true" type="tns:anotherComplexType" />
                <xs:element minOccurs="0" name="d" type="xs:dateTime" />
                <xs:element minOccurs="0" name="e" type="tns:string" />
                <xs:element minOccurs="0" name="f" type="tns:boolean" />
            </xs:sequence>
        </xs:extension>
    </xs:complexContent>
</xs:complexType>

And this is a sample of the relevant part of the response:

<letters>
    <a>0</a>
    <b>2015-02-03T11:59:18+11:00</b>
    <d>2015-02-03T12:00:00+11:00</d>
    <f>true</f>
</letters>

I suspect that because they are defining a <xs:sequence> for the elements in the <letters> part, that the .NET Serializer is expecting the response to have ALL elements present in the response? (And thus, their response breaks their WDSL definition?).

Thanks