Graham Ward, who runs Oak Stores (previously Rivenhall Post Office) in Rivenhall, Essex, has asked me to "shake the tree and see what comes out" regarding possible intermittent faults in the PO's Horizon system resulting in unexplained losses and penalties.

Computer Weekly has been running articles cataloguing seven case studies of postmasters' claims that their Horizon IT has shown unaccounted-for losses. One former postmaster in Yorkshire refused to pay £27,000 that the PO said was owed because he strongly believed the system to be at fault. He went to court but lost and is now bankrupt. Another said calls to the Horizon helpline couldn't stop deficits occurring and she started to sign accounts knowing they were wrong. She was convicted of false accounting. Another, convicted of the same charge, spent his 60th birthday in prison. A fourth sold his PO and resented repaying £11,000 he felt he did not owe.

And so it goes on - to a seventh retailer who has refused to sign his weekly accounts and is calling for a public inquiry.

The Post Office denies that there can be IT-related faults.

Graham says he had problems for five years. "Information goes missing. They said I owed £10,000 and they took £3,000 of it out of my wages."

His contract with the PO has been terminated and he is using the space for storage. Graham would like to hear from others with similar problems. You can contact him at graham@oakstores.co.uk or phone 01376 53691.

I would welcome feedback on this, too. We all work with computers and know that they can be peculiar beasts, putting stuff in a different order, for example. Perhaps that also means that when it adds the columns up, the answer could be wrong.