I believe the one under the ashtray in the cab is on the Mercedes circuits. On our 2012 that one is a "high power" outlet, rated for 25 amps I think. Check your Mercedes manual for the fuse that operates it - in the cab fuse bank, I believe.
The one at the foot of the bed is on the house circuits. Should be fused in the panel near the floor under the fridge or oven (can never remember which).
If I understand you right and these are the two 12 Volt outlets you are having trouble with, they are on completely independent circuits in our 2012 "S". Any chance you plugged the same thing into both of them - causing them both to fail?
2012 Solera "S"
Calif SF Bay Area