How can my landline and broadband be transferred without my say-so?

My internet access has ceased after someone set up a new landline at my address under another number I returned to my flat after a fortnight away to find my internet access had ceased. The following morning I phoned the Post Office, which provides my landline and broadband, to be told my account had been transferred to BT. It was news to me. BT confirmed someone has set up a new landline at my …

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