Anybody knows if it's possible for someone else to go to the immigration (Promenada), and get a tourist visa extension for me? (I don't mean an official agent, it would be my gf if that matters...)
TLDR : Answer Summary
The consensus among commenters is that the visa extension must be done in person by the applicant, meaning someone else, even if they are a close acquaintance like a girlfriend, cannot apply on behalf of the individual needing the extension. There are discussions about the difficulties of reaching the immigration office, and some jokes about the challenges of being a tourist.