Tata Docomo — unnecessarily deduction of balance

I am tata docomo sim user. Whenever i recharge my sim they every time deduct my balance. I am having this problem since last month they always say that my deduction has been done because of call.
I am using jio sim also which is having free calling facility then why will i call from docomo? In other hand i asked them to provide the details, they told me the first 6 digit no which was exactly same as my jio no. My docomo and jio sim is on same mobile so it doesn’t make any sense that ill call on my no by using same mobile.
I approached to customer care so many times but they directly refused to resolve my complaint.