diff --git a/src/Academe/SagePay/Helper/Helper.php b/src/Academe/SagePay/Helper/Helper.php
index da7b606..87c86b6 100644
--- a/src/Academe/SagePay/Helper/Helper.php
+++ b/src/Academe/SagePay/Helper/Helper.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace Academe\SagePay\Helper;
+
 /**
  * Base model abstract for models that generate XML as their main output.
  * TODO: split the currency stuff out to a separate abstract. Currency details
@@ -7,8 +9,6 @@
  * ServieceAbstract inheriting the XML functions here.
  */
 
-namespace Academe\SagePay\Helper;
-
 use Academe\SagePay\Exception as Exception;
 
 class Helper
diff --git a/src/Academe/SagePay/Metadata/Iso4217.php b/src/Academe/SagePay/Metadata/Iso4217.php
index 018fd04..53caf5b 100644
--- a/src/Academe/SagePay/Metadata/Iso4217.php
+++ b/src/Academe/SagePay/Metadata/Iso4217.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace Academe\SagePay\Metadata;
+
 /**
  * List of ISO4217 currency codes.
  * See: http://en.wikipedia.org/wiki/ISO_4217
@@ -7,14 +9,10 @@
  * Not all will be supported by SagePay.
  */
 
-namespace Academe\SagePay\Metadata;
-
 class Iso4217
 {
     /**
      * Currency code list.
-     * TODO: store this data as a PHP array, then it is easier to manipulate
-     * without the need to convert. Or maybe convert once and cache.
      */
 
     public static $data = array (
diff --git a/src/Academe/SagePay/Metadata/Transaction.php b/src/Academe/SagePay/Metadata/Transaction.php
index b608303..d3ce39c 100644
--- a/src/Academe/SagePay/Metadata/Transaction.php
+++ b/src/Academe/SagePay/Metadata/Transaction.php
@@ -672,7 +672,7 @@ class Transaction
                 "chars": ["A", "a", "^", "9", " ", "+", "'", "/", "&", ":", ",", ".", "-", "n", "("],
                 "min": 1,
                 "max": 40,
-                "default": "academe",
+                "default": "3F7A4119-8671-464F-A091-9E59EB47B80C",
                 "source": [
                     "server-registration"
                 ],