Interspire Email Marketeer API

<xmlrequest>
<username>admin</username>
<usertoken>xxx</usertoken>
<requesttype>subscribers</requesttype>
<requestmethod>UnsubscribeSubscriber</requestmethod>
    <details>
    <listid>1</listid>
    <emailaddress>xxx@fit.net.au</emailaddress>    
        <subscriberid>2222</subscriberid>
        <skipcheck>true</skipcheck>
    </details>
</xmlrequest>

It is most important that you follow the parameters accordingly.
Following the API > Subscriber > UnsubscribeSubscriber

The parameters are as follows:

UnsubscribeSubscriber($emailaddress='', $listid=0, $subscriberid=0, $skipcheck=false, $statstype=false, $statid=0)

So email address has to come before listid and before subscriberid. I spent a total of 15 minutes writing an email to the Interspire help center to see what I was doing wrong and spending 1/2 hour reading their documentation didn't do me any good either. Some trial and error try and catch helped identify the main issue. :)

Just a heads up for myself when I work on this again in the future.