After one month, I joined one of the NBFCs and realized it did not suit me well. I decided to abscond and have not gone to the office since then. Now, after 23 days, they sent me an unauthorized absence memo to my address. In that, they told me to submit my explanation within 3 days. What should I do now? Should I send my resignation through mail (I cannot go to the office directly to inform them)? What actions may they take if I do not respond to the letter?