You can check your remaining balance and data allowance in My Vodafone. You can also see the details of your data pack and TopUp.
If you only want to know how much data you’ve used in a single online session, you can see this in your dongle or Mobile Wi-Fi dashboard.
Alternatively, you can call 46210 free from your Vodafone mobile or 03333 044775 from any mobile or landline (standard call charges apply) to hear your balance and remaining data allowance. You’ll need your Mobile Broadband device’s number to hand before you call.