Help!! Heater, windows, side mirror and entertainment fault on Ford Mondeo 2015 TDCI

Hi,

I have a Ford Mondeo TDCI titanium 2015 and intermittently I have a major problem that I’m desperate to fix but Ford can’t find a fault.

every so often the electrics stop and my wing mirrors won’t move, the blowers stop, the windows won’t move and I can’t adjust the radio setting on the screen - the sat nav works but nothing else on the screen is responsive. The errors all occur at the same time. The car can be like this for a month or a day and then it randomly all comes back on.  
 

the result is I’m struggling to drive the car since the window screen is getting steamed up. 
 

for some reason the front passenger window panel works so I end up opening that window which helps slightly but it is hardly ideal and freezing at the moment! 

I can control the volume of the radio on the steering wheel only.

I have taken it to a Ford garage when the fault happened but when they switched the car on it had gone back to normal and they said they couldn’t find a fault!  
 

I’m desperate not to get rid of the car - has anyone else had this problem or heard of it? 

thank you!