Airtel Postpaid - Data not enabled

Im a small employee based in Bangalore and I work from home and for me Airtel was a service provider. I have a Airtel postpaid connection which I use for calls and internet. On *th of July I had contacted the Airtel and got plan changed. As discussed with the team, they were supposed to activated certain GB of data as per the plan starting for that data as per the plan. But unfortunately I did not receive the data benefit as per the plan and more over started receiving that my data usgae in ***%. I have checked my data usage on *th and *th July which was not even ***mb. And when contacted Airtel customer care, they say that I have used **gb of data and hence I have no data left. When I asked them to show my data usage since *th of July till date to prooves the same, they say they don't have access. I have been escalating but of no use. Everybody says will get this sorted in next two hours and arrange a call back but no one calls back. I have lost my productivity as I'm a work from home user. It's costing my bread and butter. Not sure whom to reach out to. Kindly help in my situation. I feel I'm cheated by Airtel. They boast of open network, transparency but nothing. End of the day they are mastering to cheat gullible people like me.

I would like to ask the below details of.
*. My day wise data usage since the day I changed the plan ie since *th of July.
*. What could be the reason that I activated a *gb smartbyte data for **rs on *th of July.