First complete one year, then you can ask for an increment if you feel salary is less for your job. Never threaten your employer by asking increment when you are in emergency leave. It is not professional behaviour and not good for your career growth & it spoil your relationship with your employer. Once you complete one year give a letter stating your Achievements, commitments, responsibilities in your company. Definitely you will get. If it is not working then give a resignation letter and look for another company. Best of luck.