Employer not paying salary

Hello everyone, My husband has been working with a Musical Insitution for past 1.5 Yrs. As per his appoinment letter if he wishes to leave, he has to give a 30 days notice period but the institution can terminate him with immediate effect. On 01st Aug 2016, my husband gave a very descent & formal Resignation letter mentioning of working for 30 days notice period through mail & submitted the same in their branch on 02 Aug'2016. My husband demanded for an acknowledgement and the HR refused to give & said she'll mail. They hired a New Teacher and instructed my husband to teach him his methods of teaching & as soon as he was well versed with all students & branches, they terminated him with immediate effect on 08th Aug'2016. They have issued him the pay slip for the month of July'2016 but did not credit his salary for the month of July'2016 & the 8 days of Aug'2016 as well. Whenever he calls the HR, she either keeps on pushing the meeting or doesn't respond to the calls & now giving us warning that you are not coming for meeting and we'll consider the matter to be closed. Please advice what shall be done.