Delay in Job Offer at a Media company - Should I keep on calling/Mailing them until they finally give a definite reply?

Hi, I appeared for 4 successive interviews for a job position at a media company. The very next day I was asked to submit my documents which i did within 2 days. Now i was hoping that this would result in them giving out an offer letter as they had mentioned in the mail that would also be needing my reliving letter post acceptance of the offer.

It has been almost 20 days now and they keep on delaying without giving any valid reason. They just give vague replies like they are waiting for MD's approval or they will get back to me soon. What's more is that they have not even disclosed the salary being offered, which they said they would after receiving my documents.

What should I do? is this a delay tactic? Should I keep on calling/Mailing them until they finally give a definite reply or should i just wait for their call?

this job is really crucial for me...Please help!!

i really need an insight into why a company may hold on to an offer being given...?

DhruvSinghal20 : Is this the only company on the planet? Begin to apply for other jobs. Don't panic. Don't delve deep into why they aren't giving 'Valid' reasons or why they haven't disclosed salary, etc - for all intents and purposes, treat the opportunity as lost.

Dear Dhruv,
I echo Talent Sorcerer, the employer needs you as much as you need the job. Stay focussed and let the offer reach you, if its the right one for you.
If you had cracked this interview to a level where they had asked you for your documents, you can crack other interviews as well.
Some amount of introspection at your end would be nice, such as how you could have answered each round better or any loop hole in your documentation. At the same time , don't over think.
Stay focussed on the opportunity which meets your requirement to shape your career better.
A free advice, treat ever interview as a networking opportunity at its best! Keep you expectations lowest low and focus on building relationships.
At the end of the day, you too get to know employers and work cultures, while being interviewed. Hence, job or not, keep the interactions, win-win for both.
Wish you all the best !

I am treating it as opportunity lost...The HR told me i have will have a final word this Friday... if she doesn't get back to me then...i will stop pursuing this job all together...thanks for the reply @talentsorcerer