Response from Guilherme:
The ad states from the beginning that the bed was a futon, so Santiago confirmed because he wanted to.
The problem with Santiago and his brother is well represented in the phrase "without letting us (k)now". Both of them thought that they were at their home and me and my girlfriend were the guests. So, in their mind, it was ok to get our food, not to wash the dishes (a basic rule that every guest receives when the reservation is made) and walk around without their shirts. It was not. By far, they were the worst guests that I had since July and a quick look at this page shows a little tantrum of his part.
After his request, I spent an hour of my work on a Friday afternoon calling hospitals and clinics in São Paulo in order to arrange his brother's appointment, even with very confuse instructions. Santiago didn't even bother to thank me for that. Since his brother was in such a delicate state, maybe he should consider renting a proper place with a comfortable bed (not a futon, like the ad explicitly said) or didn't depend on people stop living their lives so both of them could rest.