Salary Withheld &Compulsion To Serve Notice Period

I am working for a Pvt Ltd Company (Manufacturer). I have just completed my Probationary period of 6 months. Due to some internal politics, I am getting some work pressure & mental pressure. So I have resigned from my position after completion of probationary period and still working for another 25 days. Our HR has issued an acceptance letter for resignation in writing & by e-mail. As per appointment letter, my job confirmation will be issued by writing, but I have not provided any confirmation letter.

I have got a job in another company and have to join this 1st Dec. But our HR is compelling to serve another 20 days and purposely delaying my re-leaving and told me that they will withheld my salary for current month.

I read an article in google search that, supreme court says "after completion of probationary period doesn't means deemed confirmation."

My query is:

1.) Is our HR has power to compel me to serve notice period?

2.) Is our HR has power to withheld my salary untill final settlement?

3.) what is the remedy to re-leave at the earliest?

It is true that just completing the probation period will not make the employee confirmed and for that written communication is required. So long as there is no communication of his confirmation the employee is on probation only. Therefore, the notice pay as is required for a confirmed employee will not be applicable to you.
Relieving and making full and final settlement within a certain time depend upon the culture of the organisation. Knowingly or unknowingly many HRs follow wrong practices and threaten employees saying that the salary would not be paid or no certificate would be issued or even poor reference would be given in case of any background verification comes. These are internal policies and cannot be changed. The only remedy is to give awareness and practically it is not possible to adjust to the realities.
Madhu.T.K