Out of batery!!!

The car is 3 year old and nothing was ON when this happened, we checked.
We called MB road side assistance and they charged the battery and started the engine, connected DAS to check errors and nothing, also did a test with some Daimler Crysler battery tester and all was good!
My question, any one had this problem yet?
They don't know what is the problem, and we getted an new Renault clio 1.2L
(loaned) for free for 5 days while they are searching the problem...They will check it this week, but the tech of road side assistance sayed that could be some kind of condensator!!
has a poor reputation of drawing current even when the ignition is off, thereby
depleting the battery. have someone check for current draw....disconnect
seat controller and check current again.

has a poor reputation of drawing current even when the ignition is off, thereby
depleting the battery. have someone check for current draw....disconnect
seat controller and check current again.
But he couldn't see any faults with it.
They will check it better this week.
Thanks





