Caravan storage on Costa Brava

We have just returned from a month in Spain near Roses. We have been very curious to see storage places for caravans advertised all over.  They would drop the caravan off and pick it up for you from your chosen site (I'm guesing within a certain radius). The price included servicing and undercover storage.

I know we would need to consider insurance, but we were wondering does anyone have experience of this service? Any advice at all?