By the sounds of the original poster, the fridge was operating on 12V (beit auto or manual setting) as they were travelling. When they stopped suddenly the 12 V supply disappeared. Maybe there is an isolator in the car's power supply for the van? It is most likely a 3 way fridge because it runs on 240 V (if it was a 12 V compressor fridge, it probably won't go on 240 V either). Connect it to 240 V and it goes. A few days later and the tug's battery is still not flat, so I reckon it is the 12 V supply in the tug or the 12 V element blown in the fridge.