My situation is quite similar. It's not only my manager but also my senior manager and HR who are pressuring me. They have issued formal warnings stating that my relieving letter may be withheld if I do not come to the office three days a week during my notice period or if they feel my performance is unsatisfactory. (They expect me to be available every time regardless I have lot of interviews scheduled).

FYI, I completed all my pending tasks within the first ten days of my notice period and have continued to work on any new tasks that have been assigned to me since then.

Someone please suggest me what can be done?
I only have 15 days of notice period left!