When David Houghton returned home from a holiday, he was horrified to find the lock on his front door had been picked.

But it wasn't thieves who had broken into his home. It was British Gas.

The energy giant had taken the drastic - and perfectly legal - step in a row over an unpaid bill, even though it later emerged that Mr Houghton did not owe the company a penny.

The 34-year-old's nightmare began in July 2005, when he bought a two-bedroom flat in Willesden Green, North London, with his girlfriend Abby Simpson.

He immediately decided to ditch the property's contract with British Gas for a better deal with rivals EDF.

But the British Gas computer system wrongly continued to bill the couple.

Mr Houghton dealt with numerous threats of legal action and visits from the bailiffs, before a personal apology from the energy giant's managing director, Phil Bentley, convinced him that his troubles were over.

But when the couple went on a long weekend to New York in June last year, they returned home to a nasty surprise.

While they were away, British Gas had swapped their meter for a pay-as-you-go version.

To do so, an engineer and locksmith had sneaked into the flat by picking the locks on the front door and an internal door.

They then left a note informing the couple what they had done.

Full article here.