You were probably in breach of the parking regulations for that particular car park, as generally the regulations are one bay = one car. If the car park was that empty, would it not have been possible for you to park fully within a bay at the end of a row?
Regardless of whether the car park was busy or not, if everyone used up two spaces instead of one there would be substantially less spaces available.
The company will have got your details through their CCTV system, which records the number plates of everyone using their car park.
My advice? Pay the fine and buy a smaller car.