Just remove "DATUM PROVEDENÍ TRANSAKCE" altogether

gcconv.py

@@ -120,7 +120,9 @@ class MbankTransaction(BaseTransaction):
 
     def _description(self):
         type_, message, party, number, ks, vs, ss = self._scrap
-        message = message.replace(u' DATUM PROVEDENÍ TRANSAKCE: ', '; DATUM: ')
+        dpt = u' DATUM PROVEDENÍ TRANSAKCE: '
+        if dpt in message:
+            message, __ = message.split(dpt)
         out = []
         if type_:
             out.append(type_)