South Bengal State Transport Corporation [SBSTC] — extra luggage fare and rude behaviour

Address:

Purulia, West Bengal, 723101

I took ticket for purulia to sirkabad on 8feb 2019 at 5:40pm from purulia state bus stand.
They charged me ₹100 for my luggage.
When i asked them about the fare chart for the luggage, they behaved rudely and said that there is no such chart, there is a fixed amount we used to charge, we can charge even more more for the same.
Please do something