Hi there,
It is mandatory in Spain for every business to have a book of complaint sheets "hoja de reclamaciones", where customer can fill out any complain they have against the company, a problem with a service or poor customer service, which is the matter here.
Any company does not like getting "hoja de reclamaciones" fill out because they have to be shown to public inspection services when they go to companies to inspect their services.
So, I am sure if you mention this, and by law, they have to give it to you, they will start to listen very carefully to your problem.
Hope this helps
Maria