Airtel — unbilled usage - unethical practices

Address: Pune, Maharashtra, 411020

My bill hasn't been generated for the past 2 months and now airtel says that i've a usage of around 7.5 lakhs. It has been constantly increasing since i came back from international roaming. I had deactivated my international roaming pack long back and my data was barred as well. Now they don't have an answer and ask me to wait further. Highly unethical. Btw my credit limit is 14k. It started off with suddenly showing 1.5lakhs and now it has reached 7.5lakhs