Upvote:1
The Schengen Visa Code (12.3) states that when notifying the refusal to the applicant, information regarding the procedure to be followed in the event of an appeal should be given https://ec.europa.eu/home-affairs/sites/homeaffairs/files/policies/borders/docs/c_2010_1620_en.pdf#77
If thereβs really no information or address for appeal given in the refusal letter, I would write to the Portuguese Consulate nearest to where you live. Addresses are available here: https://www.londres.embaixadaportugal.mne.pt/en/consular-services/general-information
See this question Schengen tourist visa refused. Can I appeal for reconsideration? for advice on what your appeal letter should contain.