Last salary not credited

Dear Sir, My wife worked with reputed hospital of Baroda between August 2017 to December 2018. Due to health issues (baby planning) she gave resignation from duties on 28/11/2018 with 30 days notice period. However, she was relieved from her duties on 6/12/2018. HR person stated that management has decided to relieve her without serving 30 days notice and was informed that she will get her dues and relieving letter within 45 days of her last day. The salary credit date is not fixed in her company however she use to get her salary after 10th of every month. Hence, her November 2018's salary was not credited into her account and was told by HR that it will be credited in account as with regular salary. Even after more than 2 months passed she has not received her relieving letter and final settlement check along with November's salary. Whenever we called they promised to act in 2-3 days. Last week on 13th Feb 2019 they issued final settlement check (Notice Period and Leave Balance). Upon asking about November's salary 1st they denied pending then after insisting they checked and accepted the mistake. They promised to issue to the check on following day with relieving letter. But since then they are not responding to calls and not allowing to meet. INR 21000 is obviously huge amount for middle class people and particularly it is very important amount for me as my wife is 3 months pregnant. Please advise to pursue the issue under Labour Law.