Epsilon Senior Email Developer interview questions

Cleared first round of coding test. Rejected in the second round [ Manager and Technical ]. Not sure why, because I answered 80% of their questions and the manager even discussed about the package. Next day surprisingly, I received a rejection email and tried calling HR to know the actual reason. Not sure how they are validating the candidate. No answer to my multiple calls and emails. They don't even have sense to call back or reply back. Very bad experience.