If it's unusable, tell them and say you will stop paying for it as it doesn't live up to their advertising. Your rights are protected outside the contract. Threaten to complain to Ofcom if they resist. They'll let you leave and give you the MAC code.
I'm in London and my exchange has Sky LLU support. Coincidentally I live in the same postcode as Sky HQ so any problems, I'll talk face to face with them as I have some contacts.
I did ring technical support to get the issues fixed last Thursday -- apparently a higher level technician will call me back within '10 working days'. Hmm.
I'm not trapped by a 12 month contract, which is why I'm not too annoyed about the situation. My cabinet will get fibre fitted early next month, so I should only have to endure Sky for another month or two thankfully, which is ok by me.
I'm in London and my exchange has Sky LLU support. Coincidentally I live in the same postcode as Sky HQ so any problems, I'll talk face to face with them as I have some contacts.