Airtel — Unfair data usage calculation rate

Address:

Airtel india

I have been using internet pack of Rs 349 for two years from airtel. The said plan gives 1.5 GB of data and unlimited calls. But when I use internet for one hour the company calculate usage rate at 350 to 500 mb. So if I use internet for three hours my data is completely exhausted. This happens most of the time. And even I can't talk about this to their customer care.