The Be Bulgaria call center are pretty much head and shoulders above MOST UK ISP call centers, they have tools for the management of lines which most other UK ISPs don't have and they have excellent training and skillsets.
What you have to realise is, if you're recieving 8mb in a city center location, have you considered other factors such as the length of wiring to your premises, impulse noise/quiet line noise on your line that is counteracted by conservative noise margaining that is responsible for the simple fact that your line cannot cope with anything above 8mb?
When your line is provisioned, it is on the BLEEDING edge of what you can recieve, Be are not conservative in providing you with broadband, you are given the fastest you can possibly achieve based on the information passed to and from your router to the DSLAM.
Simple fact is, if they see that they can't bump down your noise margin to give you a higher sync, they cant, there is 101 ways of determining your line state and what it can support. Well, i lie, there is a handful, your line length, copper quality, bridge taps, impulse noise and quite line noise.
It obviously sucks that you dont think you are recieving the service you think you should have, but the problem is, a lot of customers dont realise that there is a lot more to getting 24mb than just having a BT line and being a certain length from the exchange.