Extra salary to full time emloyees

The indigenous Indian company I am working with has downsizes in March 2014 and the HR personnel told us, (not in written format) that they will provide the basic salary of April 2014 along with other remunerations(Gratuity, Earned leave in cash, and working days of March 2014). But the company now says they wont provide the basic salary of April 2014 although they paid all others remunerations, except extra month payment.

My main Query is, Is getting extra month payment our right?, or Was it just a goodwill of company to provide the extra month payment, which they can alter as I mention above? If this is our right then how can we receive it? There are hundreds of employees who suffered due to this downsizing and the volatile policy of company. Please guide us on our employees right as per IPC, regarding the extra payment, when company layoffs.