I upgraded to superfast fibre last March, speed has been fine for few weeks only then slow. An engineer came and sorted in May. Went up again for few weeks then slow again (~30Mbps instead of 120+). I have had numerous online chats with talktalk, was told to do all sorts of tests (remove faceplate etc) but no effect. Two more visits from engineers and openreach, they did their best but still slow speeds. Now I find out that I am charged +£40 on Sept's bill... this is unfair... fed up... please help!