SOAP Integration into WP PHP Plugin - php

Question

I'm tasked at using SOAP to pull in data through a WP Plugin for ease of use. I'm stuck at using the supplied auth details to get the correct data. I'm using SOAPUI to explore the request and see the possible methods/calls.
The flow should be using the FetchNewListingsIds which will give me a list of IDS which I can then put into an array object and then use that again for FetchListings with the supplied IDs - that will then give me all the details for each listing which I can then take and pull in to display
This is what I've written so far:
function property_feed_call(){
$url = "https://exdev.server.propctrl.com/v5.4/Basic/AgencyIntegration.svc?wsdl";
$user = "MindesExdevFeedUser";
$pass = "MindesExdevFeedUser";
$options = [
'cache_wsdl' => WSDL_CACHE_NONE,
'trace' => 1,
'stream_context' => stream_context_create(
[
'ssl' => [
'verify_peer' => false,
'verify_peer_name' => false,
'allow_self_signed' => true
]
]
)
];
// Set request params
$params = array(
"Username" => $user,
"Password" => $pass,
);
$client = new SoapClient($url, $options);
$session = $client->FetchNewListingIds($params);
// Invoke WS method (Function1) with the request params
$response = $client->__soapCall("FetchListings", array($params));
// Print WS response
echo '<pre>';
print_r($session);
echo '</pre>';
}
An example of how the request looks (FetchListings) when I open it up with SOAPUI is:
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:v5="http://server.propctrl.com/v5_4" xmlns:ais="http://server.propctrl.com/v5_4/AIS" xmlns:arr="http://schemas.microsoft.com/2003/10/Serialization/Arrays">
<soapenv:Header>
<v5:Credentials>
<!--Optional:-->
<v5:Password>?</v5:Password>
<!--Optional:-->
<v5:Username>?</v5:Username>
</v5:Credentials>
</soapenv:Header>
<soapenv:Body>
<ais:FetchListings>
<!--Optional:-->
<ais:mandateIds>
<!--Zero or more repetitions:-->
<arr:int>?</arr:int>
</ais:mandateIds>
</ais:FetchListings>
</soapenv:Body>
</soapenv:Envelope>
So you can see its asking for Credentials which I have just not sure how to pass it to my request. And then for a mandateIds which I can get from another method that also requires the same Credentials.