Not Providing Reliving Letter As per the Expected date

Hi, I am working for IT staffing company around 9 months. As per the company policy 6 month is the probation period,I completed my probation period and got my Confirmation letter. Last month on Feb-29-2016 was my Last working Day at client Location. ISSUE: Now the company has released my Reliving letter for Feb-29-2016 But As per the company policy one month is the notice period, so my expected Reliving Date will be Mar-31-2016. When i am asking for the same to provide my Reliving letter as per the Expected date,They are saying that we will provide until Feb-29-2016 becoz until that day only you have worked for the Client. As per the Appointment Letter, "Successful Completion of probation or any extension thereof,you will be confirmed in the services of the company,.Confirmation shall take effect only upon issue of confirmation letter and from the Date given in the letter. On Confirmation your services are liable to be terminated by 30 days notice on either side or Payment in lieu thereof.The notice pay amount shall be calculated on your last drawn basic salary. I had requested them to provide my reliving as per your company policy and now they are denying to provide it. Please help me in this regards ASAP,