Dear Prashant,
Vikram is right, the time for referral of dispute to labour court is three months, not 45 days.
Probably, you might have some confusion about the proceeding by the Grievance Redressal Committee, which of course is 45 days for completion of its proceedings as per the amended Section 9C (6) of the Act, or for referring the dispute to the labour court after the disposal of the case by the Grievance Redressal Committee (both work out about 45 days).
Naturally, the 3 months for referral of dispute to the labour court covers the period of 45 days for the completion of the proceedings of the Grievance Redressal Committee and one month for disposal of appeal thereafter to the employer against the decision of Grievance Redressal Committee.