As per previous post:
There was still this outstanding piece of work to be done. The Thermoswitch required a replacement.
I wasn't able to find this specific item anywhere:
I did order it here locally at Italauto and picked it up 2 weeks ago. It turns out the item is slightly different and is a pressure switch. In any case I made a new appointment to get this looked into and fixed. Perhaps they still could restore the old switch somehow. If not they will fit this instead. Next to this they will look into the MOT. I will write a seperate maintenance blog about that. In any case, today I picked up the car and they used the new switch instead. So all is functioning now - the airco is working but it's not very cold in my opinion. Another item off the list.
Update 8-6-2014: Today it was figured out when turning the airco switch to red it was blowing cold air. So yes, it is working. But with heavy sun on the front window, running engine and drive shaft, it's not sufficient to get the car really cold.
H/P 25 kg/cm
L/P 2 kg/cm
New pressure switch
And the picture of the backside with the numbers: