Idea Cellular — security deposit not been refunded

Address:

Bangalore Urban, Karnataka, 560035

I have closed the sim card after paying bill + additional incorrectly billed money.
There was huge discrepancies in the bill. Firstly exceutive said it 399 plan but when activated it 499. I informed the customer care, they told its 499 but you will get offer which you need to pay 399. I agreed, and i told about the internet data, they told somebody made false promises i will take a complain. Then they activated one more plan without my confirmation and charged me more. When i informed customer care they told that before activating called me 3 times but i didn't answer. They are un-professional, doesn't want to listen only. I was fed up and asked them disconnect. I had to clear all bills, i did. Then i didn't get the security money.
Asked the store they told me after 3 months i will get a cheque.
I haven't received yet.