Penlid i actually work for BT THD have u rang them? (u wont get me cause i work for NI specifically) but if u are getting a slow speed there is stuff we can do but we need to run a few test's first.
we can run a speed test and line check if u are below your speed threshold is it more than likely a BT wholesale problem which can be fixed easy enough.
Are BT breaking there contract? No your contract says up to 8 Meg.
Can we fix it? Yes but ring us