Although Bytargentina employees are very kind if there is a problem with your flat you may be really disappointed. The flat we rented was in a great neighbourghood - Palermo Viejo. When we arrived we were tired and happy to be in B.A. so we didn't really look around. But as they left we saw that the flat was in bad condition with old and dusty wardrobes, dirty dishes, the gas boiler unbearably loud, the matresses smelling old and of strong cigarette smoke, the blankets very dirty, the windows letting in a strong draught on the beds in both the bedrooms. We asked them to give us another flat but they didn't.
They changed the matress for another one that smelled even worse. An employee of theirs came. He said he agreed that some of the problems were true. He then left and the next time we saw them was the last day to pick up the keys from us. Basically, I would say, the flat was bad quality in general and this is not something you can change in a week.
I have read several good reviews about them, so you might be lucky with a better quality flat and have no problems at all. All other things were dealt fine. Still, unfortunately, I would not recommend them.