GO box credit...how to find out?

[stevec]

Currently in Austria with my GO box. Can the remaining credit be determined online? Heading from Saltzburg to Bled via the Karavanken tunnel but have diverted to Sankt Johann-Alpendorf for a couple of days. The road from the A10 seemed to be treated as part of the motorway as the Gobox was still beeping. Guy at the border said 75 Euro would cover the trip but I didn't realise that access roads would also be chargeable.