I had been working in a private firm from 1/08/2010 as manager sales & marketing till January 2018. After I have put my resignation letter they accepted my resignation but they have not paid my December 2017 month salary and 20 days salary in January 2018. They have also not paid my gratuity amount on grounds that I have not collected the outstanding dues from the market. I have handed over all company materials to them also filled up the exit forms and handed over to them. Is this legal to do this to me. More over they have given enough mental torture to me.