I am saddened to hear this unfortunate story.
Sir Jei, buti na lang at hindi ka nagsumite ng iyong resignation letter kasi mukha ngang walang valid reason para ipa-alis ka nila sa company. As long as you have the company handbook with the rules, magagamit yun as evidence kung sakali man aabot tayo sa court proceedings regarding your status.
Are they still paying your salary? Regularized ka na ba sa company na iyan? May employment contract ka ba na pinirmahan? Manager ba yung position mo or employee lang? Wala bang Labor Union yung company nyo na pwede mong sabihin yung problem mo?
Bawal yung basta-basta na termination na parang sa mga telenovela na "You're fired!" ang ginagawa. Proper procedure should be followed, and forced resignation is generally disallowed lalo na kung walang grounds yung employer na paalisin ka.
Kung di ka tutulungan ng HR nila, you can seek for advice sa nearest DOLE sa iyo. May mga help desks sila doon na pwede kang tulungan sa pag-interpret ng employment contract mo or yung company handbook. Dalhin mo na lahat ng pinadalang memos sa iyo at yung handbook para makita nila yung contents and ma-examine nila.
Kung walang tutulong sa iyo doon, try to go to the City Hall and look for the Public Attorney's Office. Baka sakaling matulungan ka nila doon or at least give you the legal advice you need.
Stay strong, Sir Jei. Sana magkaroon ng solusyon yung current situation mo. Godspeed, and good luck!