Microsoft Dynamics CRM GenerateSalesOrderFromOpportunityRequest from PHP with XML

Hi I have a php based system which interacts with Microsoft Dynamics CRM. Most of the interactions are handled using the crmsoap api.

I am currently trying to use the function GenerateSalesOrderFromOpportunityRequest which takes an opportunity and creates an order from it (yay for literal titles).

Unfortunatly the crmsoap api is a couple of versions behind CRM itself and it does not actually have the ability to use this function.

I have been trying to find and example of the XML I need but have been struggling. Does anyone have a working example of the XML?

Or can anyone see what I am doing wrong? This is what I have so far:

$retxml = $this->call(
                        'Execute',
                        '<request i:type="b:GenerateSalesOrderFromOpportunityRequest" xmlns:a="http://ift.tt/1fKiNqh" xmlns:b="http://ift.tt/1fKiLPj">' .
                        '<a:Parameters xmlns:c="http://ift.tt/191j4n0">' .
                          '<a:KeyValuePairOfstringanyType>' .
                            '<c:key>OpportunityId</c:key>' .
                            '<c:value i:type="d:guid" xmlns:d="http://ift.tt/JiuCsN">' . $opportunityid . '</c:value>' .
                          '</a:KeyValuePairOfstringanyType>' .
                          '<a:KeyValuePairOfstringanyType>' .
                            '<c:key>ColumnSet</c:key>' .
                            '<c:value i:type="a:ColumnSet">' .
                              '<a:AllColumns>true</a:AllColumns>' .
                              '<a:Columns xmlns:d="http://ift.tt/1bQEByM" />' .
                            '</c:value>' .
                          '</a:KeyValuePairOfstringanyType>' .
                        '</a:Parameters>' .
                        '<a:RequestId i:nil="true" />' .
                        '<a:RequestName>GenerateSalesOrderFromOpportunity</a:RequestName>' .
                      '</request>'
                );

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This is the XML from the WSDL:

<s:complexType name="GenerateSalesOrderFromOpportunityRequest">
  <s:complexContent mixed="false">
    <s:extension base="tns:Request">
      <s:sequence>
        <s:element name="OpportunityId" type="s0:guid" />
        <s:element name="ColumnSet" type="s3:ColumnSetBase" />
      </s:sequence>
      <s:attribute name="ReturnDynamicEntities" type="s:boolean" use="required" />
    </s:extension>
  </s:complexContent>
</s:complexType>
<s:complexType name="GenerateSalesOrderFromOpportunityResponse">
  <s:complexContent mixed="false">
    <s:extension base="tns:Response">
      <s:sequence>
        <s:element ref="s4:BusinessEntity" />
      </s:sequence>
    </s:extension>
  </s:complexContent>
</s:complexType>