Air Asia — extra charges charged

Address:

560035

I was traveling from bagdogra to bangalore on the 6th ofjan'19. The flight got delayed by 1& half hour. The luggage i was carrying had extra 4.9 kgs for which i was ready to pay the amount. But i was shocked on hearing the amount of rs.1900/-for 5kgs.
I don't think that's the charge because i have travelled with other airlines as well and i remember paying rs.100 per kg extra. How come airasia charges rs.380 per kilo. It's not valid. I want an explanation for this.