PLivo hang_up and Sequential dialing

Question

I am using plivo sequential dialing to round robin a phone call.

<?xml version = "1.0" encoding = "UTF-8"?>
<Response> 
    <Record maxLength="10800" action="http://example.com/recording-callback.php"     startOnDialAnswer="false" redirect="false" recordSession="true" /> 
    <Dial callerId="19515555555" timeout="15" action="http://example.com/action-webhook.php" callbackUrl="http://example.com/status-callback.php" callbackMethod="POST" > 
        <Number>14444444444</Number> 
    </Dial> 
    <Dial callerId="19515555555" timeout="15" action="http://example.com/action-webhook.php" callbackUrl="http://example.com/status-callback.php" callbackMethod="POST" > 
        <Number>15555555555</Number> 
    </Dial> 
    <Dial callerId="19515555555" timeout="15" action="http://example.com/action-webhook.php" callbackUrl="http://example.com/status-callback.php" callbackMethod="POST" > 
        <Number>16666666666</Number> 
    </Dial> 
</Response>

If the second user answers then terminates the call the call will continue to the end of the xml. It will call the rest of the users even when I output hangup xml. The call only terminates completely when the dialing party has hung up. Does anyone have experience terminating a plivo phone call initiated with sequential dialing