Bangalore Metropolitan Transport Corporation [BMTC] — how bmtc bus conductors cheats

I take bmtc buses on a daily basis. My ticket price is not an exact multiple of rupees ten. Let’s say 18 rupees.in case i have change, i do provide exact changes, but else i would normally pay 20.
Basic expectation is the conductor returns 2 rupees back. But strangely, around 90% of the times the conductor just would just tell that he/she doesn’t have the change and won’t return any money back. Sometime when you ask once again seeing that someone has provided change; he would still argue and not give it back. But this time would say something in kannada and be very rude; and still not return the money.
Would like to complaint against such ill treatment.