This app was mentioned in 4 comments, with an average of 5.75 upvotes
>I bought a Data pack of 4gb valid for 28 days. If I am unable to use that amount before 28 days but I load another data pack. Will my unused amount roll over to the new 28 days? If so, is there a certain amount I need to recharge to keep my unused amount?
Depends on the next recharge pack, some do and some dont
>I have 300rs loaded as talk time on my SIM. Can that only be used to talk/SMS or can I used that towards purchasing a data pack? For example, I got a message saying "offer: 1gb for 99rs, 28days validity" can spend 99 from my 300 talktime? Without visiting a store?
You should be able to, but sometimes even I am not able to use my Talktime to recharge anything in airtel and I am not sure why. Maybe you cant recharge certain data packs with it
>Is there a way I can change up my balance with a Visa credit card from America?
I am not sure, foreign cards most of the times dont work on Indian banking services you can try though
>I heard that Sims which don't have activity for 2 months expire and can't be used? Is that true? If so, is there a way to keep it active from overseas? I will return home for 3 months (then come back to India) and don't want to hassle with getting a new sim.
Buy the cheapest international roaming pack for the period you will be out of India and keep the sim in an active phone, in other words dont keep the sim in a switched off phone over a long period of time (i.e over 2 months)
BTW install MyAirtel app in case you havent, most of your queries should be resolved by browsing the app
iOS link: https://itunes.apple.com/us/app/my-airtel/id543184334?ls=1&mt=8
Time to wreck the PlayStore reviews too!
https://play.google.com/store/apps/details?id=com.myairtelapp&hl=en