Dont know all of the circumstances obviously but it seems your complaint should be lodged
against Holiday Autos rather than ATESA.
ATESA are the rental and leasing branch of Citroen and a well respected organisation here in Spain.
Knowing the track record of Holiday Autos I wish you the best of luck…
Why oh why do people insist on using 3rd party agents for car hire; at best they are a bunch of sharks. Generally speaking the savings to be made are minimal and as your case seems to indicate when things go wrong you are left up the creek without the proverbial paddle.
Always, always, deal with the rental companies directly, and stick with the majors, talk to the organ-grinder not the agency hired bloomin’ monkey who is normally hundreds of miles away and interested only in getting as much commission as possible…
Sorry this is probably not what you wanted to hear, but it happens time and time again.