It was a horrible experience in which I felt mistreated. They disrespected me. After a first call where we talked about my curriculum and they asked me some basic technical questions, they said that they would contact me for a second interview before the end of that week. After two weeks of silence I received an email from the manager apologizing for the delay, explaining that they had been very busy and asking me if we could arrange the second interview in the next two days. Before that, they asked me if I could send a letter of introduction as soon as possible. They were going to confirm the date and time of the interview. I sent the letter of presentation that same day and since then I did not hear from them, it's been three weeks. I think that at least a short email saying that they were not going to go ahead with my candidacy would have been the right and polite thing to do.