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Turned into a major problem now - not had incoming emails since mid evening yesterday. Just phoned and they said its affecting lots of customers. According to the foreign gentleman in India I spoke to "The engineers do not even know what the problem is yet - but I promise you it will be back in 24 hours!" He said he wanted to give me a big sorry!
So apparently its a completely random fault - your neighbours may not be experiencing problems even if you are. So if you are on Talktalk and yours is ok, thank your lucky stars!