Business Visa Delay

Hi All,
Let me give some history.
I worked with company 'X' on RP at 2007.
Left Qatar in 2008 after 1st assignment completion.
My company didn’t process exit hoping for new job for me. My RP expired without exit process in 2008.
I came back in Qatar in year 2009 on Business visa for company ‘Y’. I required NOC from company ‘X’ for my each visit for business visa. I left Qatar in 2010.
I came back Qatar again in 2012 on Business visa for company ‘Y’. No NOC required.
Now again in 2013 I am trying for Business visa thru company ‘Y’. But it was refused. Do I need NOC again from my company ‘X’.
I am getting visa thru local company and not getting proper response for refusal of the visa? Any help or advice. Can my old company block me? I left them with good terms.