Sub-postmasters have formed an action group following disclosures in Computer Weekly of unexplained deficits in the Post Office accounting system.
Some sub-postmasters have lost their post offices, experienced financial difficulty and faced prosecution after their accounting system showed missing funds.
The sub-postmasters insisted they did not owe the money but several faced bankruptcy or prison when they could not pay the deficits the system said they owed.
The Post Office denies any IT-related fault could have caused the system to show incorrect sums of money owed by some postmasters.
A spokesman said, "Horizon is an extremely robust system which operates over our entire Post Office network and successfully records millions of transactions each day. There is no evidence that points to any fault with the technology. We would always look into and investigate any issues raised by sub-postmasters."
Computer Weekly spoke to seven sub-postmasters, each owing tens of thousands of pounds. Journalists at BBC Wales subsequently spoke to 31 people with complaints.
A number of sub-postmasters are now hoping to form a group for those who have experienced, or are experiencing, similar problems.
Alan Bates, who worked at the post office in Llandudno in north Wales from 1998 to 2003, said he hopes the group will be a focal point for others to discuss their experiences, review past cases, provide resources and help and move the discussion forward.
Bates is looking for other sub-postmasters to get in touch to discuss what has happened to them if they have come across anomalies which they cannot explain in their accounts. He says, "A number of us are planning a weekend meeting, which you can attend for just one day, to be held at a central geographical location. Where we go from there is up to all to decide."
MP for Clwyd West, David Jones, said he is considering pressing for a House of Commons debate on the issue.
"It seems very odd to me that so many people are complaining about the same issue," he said. "I want to ascertain how widespread this problem is, and get replies to questions. I may well seek a debate on the issue."
If you would like to attend the sub-postmasters' meeting or get in touch with Alan Bates, e-mail email@example.com for contact details.
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