HOUSE RENT ALLOWANCE FOR CENTRAL GOVERNMENT EMPLOYEES

Respected sir, I am working in military engineering services Visakhapatnam which comes under ministry of defence, Government of India.
I am a civilian employee and was recruited to the post of Mate SSK in level 1 of 7 cpc through direct recruitment on permanent basis.
In my appointment order it was mentioned that I am admissible to all the allowances entitled to a central government employee.
But House rent allowance is not paid to me since date of joining. I have applied for NOC to claim HRA to my head quarters. They have been telling that you will get HRA only if you have own house otherwise compulsorily you have to take government married accommodation.
I don't have own house.
I am unmarried and staying with my parents in a rented house and ours is a joint family.
The government accommodation which is offered to level 1 employee is not sufficient to our family and hence I requested for NOC to claim for HRA. But my head quarters is not granting NOC and telling to take
Quarters or else show Own house to grant HRA.
Otherwise they asking to show a written rule that unmarried government servants are not eligible to occupy married accommodation or written rule that government accommodation is not mandatory and those who don't have own house can claim HRA.
where can I find such rules sir.

I am very much upset with these people and facing severe financial burdens. Kindly help me where can I find such rules or what way should I approach to get House Rent Allowance.

Thanks in advance.

Regards,
Praveen