I see you didn't get a warning or something so it has to be the bandwidth. I think it checks every 24 hours or something like that, so if you're <the first warning on the first run and on 160% on the next run of the checking program you'll only get a 160% mail. I think the first warning is 90%.
Best now would be to check in awstats what files are using most of the bandwidth and try to make those a bit smaller.
Pleaseeee don't double post. An admin will look into it when they have time.
Dear Bondings, please reply to my AWIT. I am waiting for your reply.