Dilato Infotech interview questions

They will asking basic questions plus test case (10 pages long) I've done all that and got through to final interview and couple days later my recruiter told me I got the job and they were preparing for salary offer but I don't know what happen afterwards suddenly they change their mind and send me a rejection letter e-mail and when I try to confront them asking for reason they didn't even bother to response. VERY UNPROFESSIONAL!