Hi Pwigg,
I think the truth is that most ISPs throttle p2p at various times, as part of their fair usage / traffic management processes. Perhaps the BT support people would understand 'p2p' rather than 'bittorrent' but then again maybe not. I doubt if there's any way you could subvert the throttling.
Probably your only realistic option is to move to an ISP who specifically doesn't throttle p2p, but I don't think you'll find one which offers this as well as a high download allowance without paying a lot of money. Zen, for example, don't throttle anything, but they have a strict download allowance and a rather high price.
Eric