Can disciplinary action be taken against a sorting assistant from RMS (Rail Mail Service) for not doing OT?

Sorting assistants from RMS always have night duties. These duties are of 12 hours. On top of this they are made to do overtime duty regularly, which affects their health due to lack of sleep. If they do not do the OT disciplinary action is taken against them. Even the rate of OT is Rs. 15/- per hour which is very paltry. There is very little information about rights of postal employees available on the net and the authorities are not co-operating to part information. Please advice.Can disciplinary action be taken against a sorting assistant from RMS (Rail Mail Service) for not doing OT?
In India, the Postal Dept is the most neglected Dept and the Govt does not bother about the Postal employees. Most of the Postal Employees Unions have political affiliations and the unscrupulous politicians really are not bothered about the welfare of the Postal employees but just to get political mileage. It is really pitiable to watch the Postal employees suffering silently.Just hope they see better days with a change of Govt. In fact, they are the most honest and uncorrupted Govt employees.