i think any speed drops are exchange/backhaul dependent so in general you can only ask others on your exchange. The QoS (or whatever they use) needs to be implemented at the TalkTalk end of the backhaul to have any great effect. The backhaul will be the weakest (lowest bandwidth) link of the TT managed chain, and as such the contention for that bandwidth will be exchange dependent.
some P2P is throttled during peak and especially Sundays on my exchange Bradwell Abbey. I suspect either Baby-Frogmella's exchange has fewer high-bandwidth users, or that the usage pattern is more consistent throughout the day meaning the backhaul can be better matched to the useage without wasting capacity during the off-peak times
In theory, theory and practice are identical.....in practice they aren't!