Another thing to try:

You can try doing what another person suggested - the Google Play settings for automatic updates. However, you can also manage when your phone sends and receives data at all and any given time. (Perhaps you already knew about this, but figuring with your current issue you should try it).

Turn off background data/data enabler. Check in your settings to see if you can adjust it to where your phone may only update widgets/apps while connected to Wi-Fi. I know how pesky and sneaky Android apps are. They love to constantly search for new information and updates. There are multiple ways to tell your phone when it can and cannot access your mobile network. You don't just have to rely on Google Play's settings. Go into your phone's settings and look for any of the following:

* Accounts & sync
* Battery & data management
* Data saver/data delivery
*Application management

I do have a Pantech Breakout in my case for sale now.
I am fairly certain you have the option of data management. But again, different Droids have it listed under different settings. But all can be found within the main settings app.

This type of control allows you to cut off all data that is being sent and received on your phone - thus telling those stinky apps to suck it! happy

It's not the cure all - but trust me, this helps A LOT. I only have 250MB, and I never run out. Because I keep those settings unchecked until I need to use them.