Wifi usage does not use up your data subscription with Globe. Please check with them why you incurred 3.2GB when you're using Wifi to connect to the net.
I can see 2 factors:
1) Data managers are not 100% accurate
2) Globe also counts your uploads (personally confirmed)
I already call globe regarding this, the csr told me that myaccount website may not be accurate since I have mydata manager and the cellular data charge in my phone setting , have the same results. I hope that's the rights answer or until my next bill , we'll see.
Another option to check data usage is:
Data track send to 8888