Begins with K.
Another thought. About a year ago my connections with 2 different ISPs began to slow down. There were many investigations and fault reports over a period of three months. It ended up with something called the "Advanced Fault Team" at BT, who finally said they could do nothing as the problem was congestion on the necox exchange.
Luckily Cable and wireless fitted their equipment in the exchange about then, so Vivaciti on of my ISPs converted their connection to one through I think a company called Surfwise who used the LLU equipment rather than the BT stuff.
My download speed immediately went from about 1.4-1.8 up to 3.4 and upload speeds improved as well. Also because it was LLU I no longer had to suffer hits to my profile due to the frequent disconnections as according to Vivacity they do their profiles in a different way.
I see from
Sam knows that Nexoc now has a 2nd LLU company. The advantage with the Vivacity connection was the one month notice contract.
If you get no change from switching to a cabinet, then maybe going LLU may improve things a bit.