As per the general conditions of Leave Rules in PSUs, Leave cannot be claimed as a matter of right. Furthermore, in exigencies of work, leave can either be refused or revoked. Moreover, it's at the discretion of the authority competent to sanction or refuse the leave under the garb of work. Now coming in terms of ground reality, if one is maintaining harmonious relations with the Boss, there is hardly any chance of refusal of leave, but if the equation is not good there comes the situation as raised under the post which is seen at most of the work places.
JSM