Picking up PHP Toolkit for first time in years to try and help point some external devs working on a WMS integration with us, and not NS experts, in the right direction. I am fairly confident that below will get them hitting the right saved search, however cannot understand how to filter the results by Internal ID of the transaction (Sales Order) which the WMS already has available to pass in, I can see it needs to be passed in to $criteria, just unsure how to format:

$service = new NetSuiteService();
$search = new TransactionSearchAdvanced();
$search->savedSearchId = "1234"; //Search internal ID
//Need to addnfilter by internal id
$request = new SearchRequest();
$request->searchRecord = $search;
$searchResponse = $service->search($request);