I had a wonderful time in Berlin, the flat is very well situated, near the subway, in a good district. The appartment was clean and adapted to our stay. I'm perfectly satisfied!
About Bernardo, I didn't have the time to see him, because I arrived later than my friends, but they said he was very kind and helpful.
I'm sure that I'll came back at the same place if I have the chance to return in Berlin!
Thanks Bernardo!