diff --git a/clients/gplan.inc b/clients/gplan.inc
index 37c595f..1e679b6 100644
--- a/clients/gplan.inc
+++ b/clients/gplan.inc
@@ -28,8 +28,17 @@ class AppointmentsGPlanClient extends AppointmentsClientApi {
     }
 
     $options = variable_get('dvg_appointments_soap_options', array());
+    // This triggers Exceptions by soap client.
+    $options['exceptions'] = TRUE;
+
     drupal_alter('dvg_appointment_soap_options', $options);
-    $this->soap_client = new SoapClient($link, $options);
+
+    try {
+      $this->soap_client = new SoapClient($this->url, $options);
+    }
+    catch (SoapFault $soapFault) {
+      throw new Exception('Appointments WSDL is not available.');
+    }
   }
 
   public static function config_form() {
@@ -388,7 +397,7 @@ class AppointmentsGPlanClient extends AppointmentsClientApi {
     return $right_dates;
   }
 
-  public function get_book_fields() {
+  public static function get_book_fields() {
     return array(
       'clientInitials' => 'Initials',
       'clientLastName' => 'Name',
diff --git a/clients/gplan_multiple.inc b/clients/gplan_multiple.inc
index 25df1fa..86f3e16 100644
--- a/clients/gplan_multiple.inc
+++ b/clients/gplan_multiple.inc
@@ -28,8 +28,17 @@ class AppointmentsGPlanMultipleClient extends AppointmentsClientApi {
     }
 
     $options = variable_get('dvg_appointments_soap_options', array());
+    // This triggers Exceptions by soap client.
+    $options['exceptions'] = TRUE;
+
     drupal_alter('dvg_appointment_soap_options', $options);
-    $this->soap_client = new SoapClient($link, $options);
+
+    try {
+      $this->soap_client = new SoapClient($this->url, $options);
+    }
+    catch (SoapFault $soapFault) {
+      throw new Exception('Appointments WSDL is not available.');
+    }
   }
 
   public static function config_form() {
@@ -316,7 +325,7 @@ class AppointmentsGPlanMultipleClient extends AppointmentsClientApi {
     return $right_dates;
   }
 
-  public function get_book_fields() {
+  public static function get_book_fields() {
     return array(
       'clientInitials' => 'Initials',
       'clientLastName' => 'Name',
diff --git a/clients/orchestra.inc b/clients/orchestra.inc
index 9a50ce7..e13affc 100644
--- a/clients/orchestra.inc
+++ b/clients/orchestra.inc
@@ -303,7 +303,7 @@ class AppointmentsOrchestraClient extends AppointmentsClientApi {
     return $starting_times;
   }
 
-  public function get_book_fields() {
+  public static function get_book_fields() {
     return array(
       'firstName' => 'First Name',
       'lastName' => 'Last Name',
diff --git a/dvg_appointments.client.inc b/dvg_appointments.client.inc
index 9bf3bea..3f2c670 100644
--- a/dvg_appointments.client.inc
+++ b/dvg_appointments.client.inc
@@ -105,7 +105,7 @@ abstract class AppointmentsClientApi {
     return strcmp($a['name'], $b['name']);
   }
 
-  abstract public function get_book_fields();
+  abstract public static function get_book_fields();
 
   public function set_booking_value($field, $value) {
     return $value;
diff --git a/dvg_appointments.module b/dvg_appointments.module
index 371f18f..ff3eeb9 100644
--- a/dvg_appointments.module
+++ b/dvg_appointments.module
@@ -50,14 +50,32 @@ function dvg_appointments_module_implements_alter(&$implementations, $hook) {
  * @return AppointmentsClientApi
  */
 function dvg_appointments_get_client_api() {
-  $modules = module_invoke_all('dvg_appointments_api_client');
-  $api_client = variable_get('dvg_appointments_api_client', FALSE);
+  $api_client = dvg_appointments_get_client_class();
 
-  if (!$api_client || !isset($modules[$api_client])) {
+  if (!$api_client) {
     throw new Exception('No appointment API client found.');
   }
 
-  return new $modules[$api_client]['class']();
+  return new $api_client();
+}
+
+/**
+ * Return the class name of the current api client.
+ *
+ * @return AppointmentsClientApi|NULL
+ *   Class name only.
+ */
+function dvg_appointments_get_client_class() {
+  $client_class = NULL;
+
+  $modules = module_invoke_all('dvg_appointments_api_client');
+  $api_client = variable_get('dvg_appointments_api_client', FALSE);
+  if ($api_client && isset($modules[$api_client])) {
+    /** @var AppointmentsClientApi $client_api */
+    $client_class = $modules[$api_client]['class'];
+  }
+
+  return $client_class;
 }
 
 /**
@@ -1923,9 +1941,16 @@ function dvg_appointments_form_webform_configure_form_alter(&$form, &$form_state
 
   $mapping = !empty($node->webform['appointment_mapping']) ? unserialize($node->webform['appointment_mapping']) : array();
   try {
-    $client_api = dvg_appointments_get_client_api();
+    $book_fields = array();
+
+    $modules = module_invoke_all('dvg_appointments_api_client');
+    $appointment_client = variable_get('dvg_appointments_api_client', FALSE);
+    if ($appointment_client && isset($modules[$appointment_client])) {
+      /** @var AppointmentsClientApi $client_api */
+      $client_class = $modules[$appointment_client]['class'];
+      $book_fields = $client_class::get_book_fields();
+    }
 
-    $book_fields = $client_api->get_book_fields();
     $components = array(
       '' => t('Select a component'),
     );