Not Being Relieved From Duties

I am on probation currently in a bank. Due to some reasons, I had to move to my hometown and I am not in a position to go back to the place where I am posted. I have sent an email to the bank stating that I am resigning. My offer letter says that I can buy out my notice period. But the officials are forcing me to come back to the place where I am posted and saying that you will have to serve the notice period there itself. When I am ready to surrender my salary in lieu of the notice period, which is in terms of my contract. Can the bank force an employee to serve the notice period at a particular place mandatorily. Owing to my circumstances I urged them for a deputation as well but they refused and they have stopped replying to me either on the mail or call on the matter of resignation. I also asked them if they notice period is mandatory, I can serve the notice period in my hometown to which they agreed initially but refused later. What shall I do now?