Teachers are not covered under payment of Gratuity Act and Rule?

Hi, My sister resigned as a Teacher after serving 7 years in a leading Private International / CBSE school in Chennai. Tamil nadu.
On relieving her, yesterday the school management denies Gratuity stating that "Teachers are not covered under payment of Gratuity Act and Rule as per the latest amendments "
The part of the question is, while appointing her in 2010 in the appointment order itself they have stated Deduction for Gratuity .... per month (as her salary was CTC based) and every month the amount was deducted.
Now on exit she is denied the payment. Is there any rule that Teachers are not eleibile for payment of Gratuity???
What is the remedy and further action to be initiated to get her eligible Gratuity from the School Management.
Any quick assistance is highly grateful and thankful.

The Bombay high court has ruled that teachers of recognised schools and colleges are "employees" as per the Payment of Gratuity Act, 1972, and therefore eligible for gratuity.
In an order passed recently, the Nagpur bench of the Bombay high court held that section 2(e) of the Payment of Gratuity Act was amended in April 2009, and the amended definition was wide enough to cover teachers.
Teachers are entitled for gratuity.
If school does not oblige,approach concerned Labour commissioner of the area for intervention.

That school have deducted a monthly amount for Gratuity (CTC) since joining and now they say, teachers not eligible and hence we have stopped deduction of Gratuity amount from CTC effective 2015!!!!!!!!! which was not notified to the concerned teachers.
but when they exit, the management is trying to take a chance of cheating the teachers.

Dear Nathrao,
Kindly share the citation of Bombay High Court Nagpur Bench ruled that teachers of recognised schools and colleges are "employees" as per the Payment of Gratuity Act, 1972, and therefore eligible for gratuity.
Regards,

Teachers are entitled to gratuity, says high court | mumbai | Hindustan Times

Hope this is applicable to Chennai schools, as well all over India....... The relevant HR madam is telling that NO Gratuity based on some amendment made in 2016 to the Act, which she is not ready to disclose what is the amendment.... what is the remedial action to proceed further and get the eligible Gratuity, that too, which was deducted from the salaries of individual teachers

Approach labour officer of the area for clarifications.