Non payment of interest on state govt backed bonds

Sir, 

I am secretary of a  exempted Provident Fund Trust of a unit of Steel Authority of India Ltd ( A Govt of India Undertaking). Trust having some investment in PSIDC ( Punjab State Industrial development corporation) bonds, a State govt. backed bonds. From Sep 2013, PSIDC is not paying the interest on the same. We have done several correspondence and telephonic conversation. In spite of all, they are telling that there is fund crunch so unable to pay it now but will pay later as and when get the money. 

So, It is requested to kinldy suggest me some way to come out of this situation.

What are the legal remedy or other way for the same

Thank in advance