Finished contract

Hello good day.!! By the way I'm Alan, I'm working as a waiter staff in lebanese restaurant. I'm working there for 2 years.  Actually,  I am resigning for my job.  But sad to say till now the company does not release  me.  I made resignation letter last July 2 months befire my contract will be ended.  Our area manager doesn't get it and always satmying we'll talk about that.  I'm  always updating when he visited our branch.  Till the time that he go for vacation.  When he back for work i till him that  I made my fixed decision.  Still the same answered.  Last September 28 my contract really over.  I really make a way to fixed everything.  The office call me that i need to report.  We talk officially with the HR and COO.  We really close the deal and oir COO asked me what date I'm going to go.  I answered October 20th,  because i give time for them to train employee for the vacant position.  And that we close our deal.  The deal is over and i always updating because its 20. I go at the office asking why? I'd waited there for almost 3 hours before the HR talk to me.  And till me I'll be ended November 5th.  Because it has 1 month effectivity as the resignation letter signed by the COO.  I insist and nothing but to work till November 5th of this month.  But now i let our chef updated the status of my exit. He called our area manager and sad to say he told that i will ended till 15 of this month . Its really disappointing.  They are unprofessional,  they don't have one word.  They are breaking the law of contract.  Please i need your advice on what to do right now against my company. Hoping for a positive feedback. Have a nice day ahead.