Notice Period and Compensation
As you have resigned, you need to serve the notice period. The organization has the right to accept the resignation and relieve you earlier than is provided in the service condition. However, there is the principle of legitimate expectation. According to it, as per the service condition, you could expect to serve the employer for three months. When the employer is refusing to allow you to serve the full three months, the employer has committed a breach of the service agreement and hence has to compensate you. Therefore, you can ask for payment for the remaining portion of the notice period as per the Contract Act 1872.
Legal Basis for Compensation
According to Section 37 of the Act, the parties to a contract are under the obligation to either perform or offer to perform the promises which have been agreed upon under the contract. You have attempted to perform your part, but the opposite party is refusing to perform its part, and hence compensation is payable as per Section 73: Compensation for loss or damage caused by breach of contract. When a contract has been broken, the party who suffers by such breach is entitled to receive, from the party who has broken the contract, compensation for any loss or damage caused to him thereby, which naturally arose in the usual course.
You can raise a demand on this basis.