DRDO — Toll tax exemption for disabled person in national highway

Address: 560093

Respected sir,
I am a physically challenged person and working in central government job.
Recently i bought a car and modified as per my disability. It is a invalid carriage registration.
Now when i drive my car in Bangalore - selam highway all tollgates are forcing me to pay the toll in-spite of showing my disability ID to the toll person.

Please somebody can help me to get the proof for getting toll exemption in highway.
my mobile number is [protected].

With regards
Manoharan