Dahdf, goi is delaying in giving noc for interview

I've joined as an employee in DAHDF on March 2016 and my probation period is 2 yrs, my pay scale is [deleted], GP-4200, I have applied for the post of Assistant Registrar at NIT Hamirpur through proper channel in the month of Nov, 2016. On 22nd June I officially came to know (email from NITH) that NIT Hamirpur has shortlisted me for the online test/ interview which will be held on 5th July, 2017 and they have also mentioned on that mail to submit the soft copy of NOC and Integrity & vigillance certificate to the office by 27th June and hard copy on the day of interview. I have not received any official communication from the department regarding NOC after submitting the application through proper channel. The day I got email from NIT, I immediately sent an email request (on 22nd June) to get NOC from the Department and as Friday was a Restricted holiday and Saturday and Sunday were holidays, they could not put up my file and ultimately I could not submit the soft copy on or before 27th June and till date I have not received either the hard copy or soft copy from the department. If department posts the hard copy to me It wont reach by me before 3rd July (I have to fly for Interview). I have communicate whole problem to my department and also requesting by phone to most of the staffs in the department and everybody is saying "we are trying". I don't think I will get the NOC before time. What should I do? need legal advice