Notice period pay

Hi, I work as Regional Head with Pvt Ltd company n a confirmed employee and my notice period is 3 months . • Earlier I was asked to resign by my ceo and take up consultancy work with organization which I refused because I was a confirmed employee and even if I had become consultant there was no commitment. • On 2nd Dec finally I decided to resign and move on and served my 3 months notice period .Suddenly after my resignation my performance came in picture and I was told i am under performer. Even after receiving such a de-motivating and disheartened mail I replied what I have done and attached appreciation and responsibility mails I had received . • After few days I got a separate mail and fresh mail from Newly Joined GM-HR which said we understand your situation and we are ready to give you 1 month notice period pay for which again I replied and said i have already resigned and pls relieve me as per policy i.e 3 months notice period pay or time than there was no response from organization side . • Suddenly on 10th Dec 2015 there was a revised policy was sent which was again a surprise and to add to this Surprise based on revised policy which is not applicable to be I was given Performance improvement plan after my resignation • Again I replied to mail received from GM –HR and explained I am on notice period and revised policy is not applicable to me and I am yet to receive any revert . All these series of events are indicating that an employee cannot serve his notice period and company can change their policy any time in their favor. Pls suggest the way forward Regards Gaurav