WTF

I need a bit more info to help you out properly.

Are you dealing with data that disappears after restarting your phone; like it’s just a display glitch or a sync issue? Where are you seeing data being 100% used. Or are you seeing unexpected overage charges on that $534 bill? Maybe both?

Here’s what I’d do first: log into Self Serve and check your real-time data usage breakdown. Then restart your phone and see if that 1GB pops back up; sometimes it’s just a display refresh. Also, grab a screenshot of your bill showing the overage charges.

Once I know which problem is bugging you the most, I can point you toward the right next steps, whether it’s disputing charges or troubleshooting. What’s hitting you hardest right now? 

When you activate a plan or change one, you do not get access to all of the plan's data right away. You only receive a prorated amount. If you had just activated, then the billing cycle would be within a couple of days and only a small amount of data would be available to you. More can be found here: Rate plan proration explained | Koodo Mobile

When you check self serve, it would tell you how much data is available to you during that period. Additionally, did you receive a text saying you maxed out the usage? As you will be shut off of data once you max it out and if you keep using it, will be charged more.