First of all let me clarify that we have labour Law enforcement officers in the state. Their duty is to ensure that no employee is paid less than the notified minimum wages. It is true that the employer can have different heads for the salary and need not necessarily be the same patterns with basic wage and Dearness allowance and in the same amounts as prescribed but what is to be ensured is that the total (gross) salary at any point of time should not be less than the Basic and DA as prescribed by the government.
In your case there is no increase in the gross salary. This is not fair especially in respect of employees for whom minimum rates of wages are fixed. I can also say that in respect of managers they should be following a more employee friendly salary structure and the same would be much above the minimum salary fixed for them. Please note that minimum wages is fixed not only for the workers but it is fixed for managers also. From my experience what I have observed is that managers are paid ten times more than the statutory wages but for those who really work they humble to bring even parity to the one fixed by the state. This will make the workers discontent and they will think of a possible way to get their rights by joining hands, the collective bargaining, by forming trade union. Once a Union is formed, then the entire blame will be on the workers. The employers will turn hostile and will do anything that they can do against the workers, let it be closure of the undertaking!
But the above situation will not arise in a locality where a good Labour (law enforcement) officer is available. He will step in to action and see what are the actual benefits extended to the workers and if he identifies anything wrong and illegal, will book the employer and ask him to be fair. This will improve the industrial relations. At the company level also we shall have a person, Personnel Manager/ HR Manager who can be sympathetic towards the employees and can advise the management of the pulses of the shop floor employees, their grievances and probable disputes which may arise if not addressed and solved. He is expected to be a bridge between the employees and the employer and his advices should be given value by the employer. Then more than half of the disputes could be solved.
Now coming to the matter of bonus I would say that bonus is not a gift that the employer can offer on the occasion of Deevali or Pongal. It is a right for those whose salary does not exceed Rs 21000 per month. There is a formula to calculate bonus and the employer should follow it. The rate of bonus, which will depend upon the profitability of the organisation, shall vary from 8.33% to 20% of basic wages and dearness allowance that an employee was paid during the last financial year. When the salary increases due to increase in the DA, the bonus also will increase.
The same is the way of calculating leave encashment. Leave is actually for availing and not for encashment. As such, the practice of showing it in the salary lacks legal backing. When you say that it is part of salary, it should be interpreted that no employee will be allowed to take leave but at the end of the year the employer will pay cash equivalent of leave. Again, when you encash it, it should not be fixed sum but it should be equal to Basic wage and DA. Suppose if you encash 15 days' leave, the employee should get wages equal to 15 days and that should not be less than the 15 days' daily average of basic and DA. For an employee with salary of Rs 20000, the daily average wage should be Rs 769 and this should be multiplied by the number leaves encashed. For example, if an employee surrenders 10 leaves, he should get Rs 7690 and so on. You cannot fix the leave encashment without reference to the number of leaves. What is the relevance of 4.2% is not understood.