He wrote to cancel the contract, but somehow they never carried his request out, so the contract never got removed from their system. It was their mistake, but he couldn't ever it corrected, even though he had proof he'd written to them to cancel. So you're right, they have no power to keep you on a non-existent contract. Equally, he had no power to make them correct their mistake, no matter whom he spoke to, or how many times he contacted them. Meanwhile, Vodaphone sold his debt at 10% face value to a debt collection company, who kept up the stream of letters threatening the bailiffs. In the end, he coughed up the £170 pounds they said they wanted rather than continue to carry the stress of it all.