F5 Software Engineer interview questions

I applied in mid December 2016. And I was contacted by f5 recruiter in Mid January 2017. Recruiter setup interview with a Software Engineer. The interview lasted for about 20 - 30 minutes. I was asked to write a simple C program on collabedit. At the end of the interview, the interviewer gave me a positive feedback. He said I should expect to be called for on-site interview. After a couple of days, recruiter reaches out to me and asked me for my availability for on-site interview. After I sent him days/times, he replied saying that he made a mistake in his previous email and that he has not received a final decision yet for my interview from the hiring manager. It could be a genuine mistake but, imagine how you would feel to be told it was a mistake after you rescheduled other interviews for this one. I emailed the recruiter a few times and he told me there is no update. Then in late March 2017 I received a generic rejection email.