Bonus is paid for the work that you have already put in - so your company has to pay you the bonus if you are eligible under the bonus act. A lot of companies club ex-gratia as part of the bonus (ex-gratia is the amount over and above the statutory provisions as per the bonus act). So you have to see if your bonus is The bonus or has a large ex-gratia component. That apart, as I said bonus is for the service you have "already" rendered and hence should be paid.
Increment on the other hand is an upward revision in salary to be paid for the service that you will put in "future". So if you do not work with the company anymore, there is no question of increment. Also you have mentioned that in your company increments are "effective" September. That means the revised salary will be for the period September to August of next year - a period when you will not be with the company. So you will not earn a salary from the company during that period and since the increment is part of the salary, you are not eligible for the increment.
Increment on the other hand is an upward revision in salary to be paid for the service that you will put in "future". So if you do not work with the company anymore, there is no question of increment. Also you have mentioned that in your company increments are "effective" September. That means the revised salary will be for the period September to August of next year - a period when you will not be with the company. So you will not earn a salary from the company during that period and since the increment is part of the salary, you are not eligible for the increment.