My 2001 C320 does sometimes not recognize my key and I am unable to remotely unlock the doors and start the car. Most of the time, it works just fine but I had to call AAA 3 times already....only to cancel a tow when the key all of a sudden starts working again without a problem. When it DOES NOT work, there is no indication the car recognizes the key at all....no sounds, flashing, NOTHING. Just like you were clicking a key of a completely different car. Again, most of the time it does not work I will just wait 30 minutes or so and then it'll work again.
Any ideas and/or help with this is greatly appreciated!