Union Management Agreement - Public Sector Undertaking

I am working in public sector undertaking as sr. Asstt. The total strength of this company both executive and non executives are 1500. My query is related to management that the competent authority of the company change all old union management agreement related to basic facility facilities related to conveyance, medical, canteen and compensate ground without discussion of present trade union. Please confirm whether the top management take this type of step without complete any agreement with present trade union and they are valuation the trade union right or not.
Also u r advice me the latest book related to trade union right related to public sector undertaking.
Hoping to it early reply.

There is no information in the post about the type of settlement whether it was a proper settlement signed u/s 18(1) or 12(3) of the Industrial Disputes Act,1947 or a mere memorandum of understanding informally signed by the parties, whether the conditions of service in the settlement have been revised unilaterally by the Management when it is in currency or after its expiry.
Any trade union whether registered or unregistered can espouse the cause of the workmen if it has got sufficient representative character and so authorised by the workmen before the management for redress and in case of failure can approach the Conciliation Officer by raising a formal industrial dispute under the ID Act,1947.