Hey @Jugal
Welcome to the Community 
It's important to note that your month is always billed in advance. Your first bill will include the charges from the day you've activated the service + 1 month. More info is available on our support page, though we'd also suggest to download your detailed in voice (PDF version) to confirm the dates and amounts billed. More info to help you understand your online bill can be found here and here.
Overall, since you've terminated the service after your first invoice was issued, the adjustments will be pending until your final invoice is issues (the next bill). If you've used the service for 1 day only, we'll automatically waive the remaining 30 days of the month. That being said, to avoid any late fees we would suggest making a payment to cover your current account balance as well. Once we apply the credit, it will be refunded to you.
Hope this helps!
