diff --git a/combo_plugin_nanterre/views.py b/combo_plugin_nanterre/views.py
index a7e660c..77d5835 100644
--- a/combo_plugin_nanterre/views.py
+++ b/combo_plugin_nanterre/views.py
@@ -54,6 +54,9 @@ def saga_transaction(request):
     num_factures = request.POST.getlist('num_factures')
     email = request.POST.get('email') or request.user.email
     error_url = request.POST.get('error_url') or '/'
+    # nettoye la session à chaque transaction
+    if 'saga_retour_synchrone' in request.session:
+        del request.session['saga_retour_synchrone']
 
     urlretour_asynchrone = request.build_absolute_uri(
         reverse('nanterre-saga-retour-asynchrone')).rstrip('/')
@@ -124,14 +127,20 @@ def saga_retour_synchrone(request):
     if (isinstance(saga, dict) and saga.get('err') == 0 and
             saga.get('data', {}).get('etat')):
         etat = saga['data']['etat']
-        if etat in MESSAGE_BY_STATE:
-            logger.info('[rsu/saga] retour-synchrone: idop=%s etat=%s',
-                        idop, etat)
-            messages.add_message(request, *MESSAGE_BY_STATE[etat])
+        if etat == 'paye':
+            logger.info('[rsu/saga] retour-synchrone: idop=%s etat=%s', idop, etat)
+            request.session['saga_retour_synchrone'] = saga['data']
         else:
-            logger.error('[rsu/saga] retour-synchrone: idop=%s '
-                         'receive unknown etat=%s', idop, etat)
-            messages.error(request, ERROR_MESSAGE)
+            # on nettoye la session
+            if 'saga_retour_synchrone' in request.session:
+                del request.session['saga_retour_synchrone']
+            if etat in MESSAGE_BY_STATE:
+                logger.info('[rsu/saga] retour-synchrone: idop=%s etat=%s', idop, etat)
+                messages.add_message(request, *MESSAGE_BY_STATE[etat])
+            else:
+                logger.error('[rsu/saga] retour-synchrone: idop=%s '
+                             'receive unknown etat=%s', idop, etat)
+                messages.error(request, ERROR_MESSAGE)
     else:
         logger.error('[rsu/saga] retour-synchrone: idop=%s '
                      'receive bad response=%r', idop, saga)