Could anyone out there please help me with this -

I live in a university grounds, so am inside the university intranet. I pay the university IT services for access by periodically topping up my account. Usually I run up costs to about $10 weekly.

In the last week, i have been debited more than $30 on two separate days. The log shows that on those 2 occasions, I downloaded about 1000 Mb from the Australian Academic Research Network. That is complete rubbish ..

IT services says that its investigations show that all the downloads came from my own IP address. So that excludes anyone hacking into my account from outside. Or does it? Could my IP address be faked on another computer?

That could mean being hacked by, say, lurkers on a chatboard like the Zone, where our IPs can be seen. Is this possible - and are there any other possible explanations?

I can't understand why the huge downloads come up as from the AARN. Surely a hacker would be downloading junk from various commercial sites - in which case the big bytes would have been on (i) (international) or (d) (domestic).

Any comments and advice would be most appreciated