I am using Airtel Xstream from last three months and did a one time payment of around ₹2800 for 100mbps plan + ONT router. This is the last month. I paid for it on around 2 April and it was installed and activated on 8 April. As of today(16 Jun 2021) I received and email of 90% usage warning. And it says that end of billing cycle will be after 9 days from today i.e. 25 June. So how does this exactly work? Shouldn't the billing be done on 8 July as it will be 3 months from installation? Why is it on 25 June??