Blacklist in placements

I'm shortlisted for some company and I have to go to Vellore tomo, but I got my pending project work and I really don't feel like going tomo. (Yes, I shouldn't have applied in the first place but the option window got over before I could change). now it's said that I'm gonna be blacklisted if I don't go to Vellore. any idea, if I'm blacklisted, how many days will I be blacklisted for and to which guy's legs should I be holding for forgiveness