My wife and I are coming from Straight Talk where we enjoyed crappy intermittent service, sub-par plan phones and the joy of receiving the same text message six times in a row, or not for days and sometimes not at all. The one thing we did enjoy though, seriously, was the unlimited data. Never ones for streaming video, we did however stream Spotify and Amazon MP3 music files completely ignorant of how much data we were using.
Now we are in panic mode having come to Verizon for (much) better phones , terrific service and a ghastly 4GB shared data plan . Within the first 48 hours we had already used up over 500MB of data just updating apps that were already out of date on brand new out of the box phones (honestly we should have been given a 72 hour grace period to update all of the pre-installed apps that came with the phone).
Instead of nailing customers with data overage charges, Verizon could carve a niche out for themselves in the top three providers by copying the Straight Talk model of dropping the user to 2G speeds unlimited after the data plan is exceeded.
Now I am a slave to the My Verizon Mobile app to check data usage several times a day.
Do you have broadband internet with a wifi router at home? If so, I would suggest connecting your smartphones with your home wifi. There are settings in the Google Play Store so that you will only update apps via wifi.
Additionally, simply save the MP3 files to your phone and play them right from your phone.