Canara Bank — ecs mandate charge

Address:

799004

My name is deep saha.
I have an account.
Canara bank, battala branch, agartala, tripura
Recently i have been charged 354/- for ecs mandate charge.
In my account 2 time in this month of december
Dates are 15/12/2018
21/12/2818
I wanna know that what basis bank is charge 354/-in mandate charge
I can, t just ignore paying 708/- month for mandate charge
This is my hard earned money
Pls refund my money as soon as possible.
Thank you