In Portugal, all accommodation providers must offer access to the official Livro de Reclamações (Complaints Book), which lets guests file formal complaints about goods or services. 

You can submit your complaint online at www.livroreclamacoes.pt, where you’ll complete a form with your personal details and the issue you experienced. Businesses are legally required to respond within 15 working days, and your complaint is also sent to the regulatory authority ASAE for review. A physical Complaints Book must also be available on-site at the hotel if you prefer to file your complaint in person.