Air Suspension w212 2012

I have a E200, 2012. The rear of the car was on the ground after about 1 hour with the engine off. After a week of this I brought it to the garage and they changed both air springs.

Now the rear of the car is on the ground after 24 hours and if its cold ( under 0 C ) the car wont rise. However, it will rise in the afternoon when it is warmer. 


Any ideas?