Relieving letter & Salary

Hi Everyone, Can you please help me to understand if anything can be done as my employer is not issuing me my relieving letter though i have worked with Organisation for approximately 2 Years. As per appointment letter i was asked to serve notice period of 1 Month and i was able to serve 13 Days only.I sent them resignation email (which they never accepted/acknowledged). I kept them informed via email that i wont be able to come to office going forth but will be available if in case any help is required. They didnt issue me entire months salary and they are denying relieving letter and no-dues certificate as well.They are stating that i haven't served notice period so wont be eligible for relieving letter(which is very imp. for my future prospects). Clause as per Appointment letter(for termination of services by any of the parties)-On satisfactory completion of probation, either party may terminate your employment at any time by giving to other party written notice of 1 Month. However the company, at its discretion agrees to terminate the employment by payment of 1 Months salary in lieu of the notice. Notwithstanding the above, the company reserves the right at all times to terminate your employment forthwith without notice or payment in lieu of notice by the way of punishment for misconduct under the companys service rules. In such an event, without prejudice to the companys right at law and/or under other provisions of this letter, the company shall pay only salary earned by you to the date of termination. By employment with the company, you expressly authorize the company to deduct from any payment due to you at any time including from termination or severance payment, any amounts owed by you to the company unless otherwise prohibited by law. The Company shall be entitled to offset payment of any pro-rated allowances, etc. against salary due and to withhold amount that may be required by the relevant authorities. Kindly suggest the way forward. Regards