Calculation for gratuity - employer says they show 50% of consolidated salary as basic salary in form 16

I have come across a case of payment of gratuity. Wherein the employee who has put in a service of 10 years and she is being paid consolidated salary. The concerned employee upon resignation has put a request to release the gratuity basis on the last consolidated salary. The monthly salary slip also show that the salary is being paid on consolidated basis.
Now the employer says they show 50% of consolidated salary as basic salary in form 16 hence they will calculate gratuity on 50% of consolidated salary only.
This case seems to be interesting one. I would like to know the opinion of all you expert guys.

What does her appointment letter say about her salary - consolidated or otherwise?
When the salary slip shows her entire salary as a consolidated one, the employee has the advantage to hold it so for the purpose of gratuity under the PG Act,1972 though the employer contradicts the same by means of his own another record like Form-16 issued under the Income Tax Rules.

Dear Umakanthan,
Thanks for your valuable update on the issue. The candidate though working since last 10 years had not been issued any appointment letter.

In that case, let the employee place her reliance for the claim of gratuity based on the consolidated salary as mentioned in the periodical salary slips. By the by, Have you any idea about the EPF contributions?