Airtel — wrong billing and duping customers

Hi,
I have been getting bill with previous month dues every month from airtel. I have raised compalints last 2 months and i was told there is some technical error wgich is generating such bills and will be fixed. But to my amusement, they are not fixing this error at all. Its not because they cant fix it, but using such cheap error techniques they are looting the gullibale cutomer. Because some customers will not check. How come such a big vompany is not able to fix this error. Payment is not getting updated properly, since last 3 months? How can we belive them?
Why there is no mechanism to npt correct this. Im sure they can correct it, but they are dealing with this secretly looting cutomers. I will be filing a case against them soon if this continues.

Regards