Norham Post Office, just a few hundred yards from the Scottish border, is one of several across Berwick borough earmarked for replacement by an outreach service.
Well-known butcher, David Foreman, representing Norham's business community in the campaign to save the post office, claimed that Post Office Ltd was using the nearby border as the postal boundary for Norham.
"It means all the businesses over the border are not classed as customers of Norham Post Office," he claimed.
He has drawn up a list of 81 businesses within a three mile radius of Norham which employ over 300 people and believes that is more than sufficient to justify a post office in the village.
However, a spokesman for Post Office Ltd said: "We do take into account who uses post offices and where they come from.
"The branch access report for Norham shows 200-299 customer access sessions per week.
"These figures will be based on the number of customer transactions over a three month period and then averaged out over each week."
Businesses are particularly concerned at the prospect of having to travel to the nearest alternative post offices in East Ord or Cornhill if they miss the two hour visit by the outreach service.
"Very few companies are going to be able to get to the outreach service when it's available due to work restrictions," explained Mr Foreman.
"I run two businesses and personally I have estimated that the loss of the current service is going to cost my company in excess of £2,500 per annum.
"This is how much it would cost to travel to Cornhill or East Ord to deposit cash and send parcels from my internet company through which I guarantee an overnight delivery. Therefore, a two hour postal slot is of very little use to me," he added.
Meanwhile, other communities across the borough are finalising their input to the consultation process which closes on August 11.
Anne-Marie Trevelyan, Conservative candidate for Berwick, has also vowed to carry on her fight against the proposed closures.
She said: "When the consultation period started, I wrote immediately to Adrian Wales, the man in charge of our area closures.
"I asked for simple data for each of the proposed closures, such as profitability and usage, and by whom.
"Post Office Ltd have told me that they are unable to provide such information 'partly because of the inclusion of personal data and the prejudicial impact it would have on the commercial interests of both Subpostmaster and Post Office Ltd'.
" I am astounded that we are not allowed to know the reasons for the closures. Some of the proposed closures, and some of those being kept open, make no sense at all. Without the basis for closure, it seems like these decisions have been made and any submissions we give will not be taken into account."
Post Office Ltd went on to say that the availability of such information may give rise to speculation about the sustainability of the branch and any associated retail business which in turn could lead to a series of forced closures.
"This is a ludicrous response," said Mrs Trevelyan. "If a Post Office is being closed despite being profitable, then what is the basis for this closure?
"I do not believe that the Post Office have made reasoned, or informed decisions about their closures with the local communities.
"If they continue to refuse to give us more information, we must assume they do not care which of our most rural communities they damage most."
Post Office Ltd is proposing to close post offices at North Sunderland and Scremerston and provide replacement outreach services in Norham, Lowick, Milfield, Bamburgh, Ancroft and Doddington.
Mrs Trevelyan added: "I will fight with all the local residents in each of the affected areas to prove to the Post Office consultation board that we must keep our services in these most rural and isolated villages.
"I will be submitting detailed evidence showing why each of our post offices should remain open as a key part of our community.
"The Post Office's disregard for the democratic consultation process, despite repeated requests to give us more time to gather all the evidence we need to prove our case, will not stop us from fighting for what we know to be essential to our villages."