Gratuity Denied Due to Salary Account Mix-Up: How Should I Proceed?

I joined the company on September 25, 2017, and left in June 2022 (4 years, 8 months, 24 days). For September and October 2017, I received a salary from the sister concern, and until my leaving date, I received a salary from the same account. However, the company is denying paying gratuity now because 1 month and 5 days' salary is from another account. Can someone comment on how to proceed further?

From October '17 to June '22, you received a salary from the current employer. The liability for the payment of gratuity rests on the establishment, and your service with the current establishment falls short of the statutory minimum limit (i.e., 5 years, even if we go by the liberal interpretation of 4 years & 240 days of continuous service). The service in the sister establishment would not count. According to the provision of the law, any other interpretation would require much more facts to equate the two establishments.