I have had my W205 C-Class Estate since last September but not done many miles over the winter in UK. Two weeks ago, I drove down to a holiday home in South West France and really enjoyed the trip. I was very pleased with my previous W204 but this was better in every way. Until yesterday morning that is. Went to the car and keyless opening not working. Temporary failure I thought so pressed the fob button, still won't open. Ah, try the other key fob - that doesn't do it either. Ah, simultaneous battery failure in two separate fobs? Put a new battery in - no difference.Simple solution, use the emergency key. Oh, that goes in and turns but nothing happens. Tried emergency key from second fob, you've guessed it. Really getting annoyed now. Browsed forums and was reminded that the Mobile.me app has an unlocking function. At last, car opens. Remove start button and key fob starts car. This feels like progress. Contacted Mobilo breakdown and car is now in nearest Main dealer. They couldn't get it to unlock either. I can live with occasional glitches with the electronic access system but it is a bit rich when the old fashioned back up mechanical key system also fails. Good job I wasn't 200 miles from home in an underground car park when it happened. No mobile signal, no app to gain entry. Not good design Mercedes! Why does the car only have one key operated lock for manual entry, even a second key accessible lock in the tailgate would have saved the day? Should get a call tomorrow with an update and will post results.