There are a few other things that could be at issue here.
Thing 1) I am on a $49 plan with Telecom, that has a 5Gb cap and full speed data access. This plan has a cap on it but no throttling, in other words I expect from Telecom to get a pretty hot speed on this plan. I downloaded a torrent this morning (as I do every Sunday morning) and I did get a good speed. Well over 100kB/sec. I would expect that on this plan - it is a high speed plan.
Telecom also have the Go Large plan at $49 - it is the same price. It has no data cap, so something else has to give. The thing that gets cut back is speed. You can't realistically expect to get the same speed you had before on this plan. If you did, I would be really annoyed, because I am accepting less data cap for speed.
One of the plans is for unlimited data, the other is for unlimited speed. Take your choice. That said, 5kB/sec is pretty low, although I think 30kB/sec would be pretty acceptable on the Go Large plan.
Thing 2) Every BT downloader has just switched over to Go Large, and every single one has had exactly the same idea, that is they can now leave their BT client running overnight to download their stuff without any penalty. The thing is, everyone is trying it out RIGHT NOW. The number of users doing this must be huge, the bandwidth pool is limited. Limited divided by an unusually large number = a small amount of bandwidth per user. Perhaps over the next few days people will have downloaded everything they want to, or have finished experimenting with unlimited bandwidth, and the bandwidth allocation will become more normal, as not every user will be downloading at the same time. Perhaps Telecom will tune their Go Large pool based on what they have seen. Either way, it takes time - it takes time to see the patterns. You can't predict this behaviour.
The best you can do is ring the ISP and tell them they have an issue (remembering the rep you get on the other end of the phone is not able to fix it all straight away).