I've used 27GB in 11 days this month, I'd say that's typical of my usage, there's no way I'm going over my FUP limit. I don't use any P2P software so I doubt my upload amount is very significant.
I haven't had a warning email either, I presume they still send those out... I had one about a year ago, sometime at the end of the month saying I was 10GB away from breaking the limit at the time.
BT_Care has replied to me via PM and has passed the problem on as a fault:
Thank you for running that test. Looking at that result your Broadband does seem to be performing below the acceptable level. I have reported a fault to our suppliers and they are currently investigating this and have made a few adjustments to your line.