// Login to the Fidelity service
function fidelity_login() {

    $url = "https://cat.fidelity.co.uk/gateway/wl/iam/v1/token";
    $data = 'context=login';

    $username = 'test_user';
    $password = 'REDACTED';

    $args = array(
        'headers'   => array(
            'Content-Type' => 'application/json; charset=utf-8',
            'Authorization' => 'Basic ' . json_encode( $username . ':' . $password ),
            'apikey' => 'b005892b-3e28-4732-9d98-4619a44233a0',
        ),
        'method'    => 'POST'
    );

    $result = wp_remote_post($url, $args);

    if( !is_wp_error( $result ) ) {

        print "<pre>";
        print_r($result);
        print "</pre>";

        die();

    } else {

        print "<pre>";
        print_r($result);
        print "</pre>";

        die();

    }

}
add_action( 'wp', 'fidelity_login' );