A seller on the online marketplace eBay has threatened to sue a customer in a row over negative feedback.
Seller Joel Jones says the feedback posted on his eBay profile page by Chris Read, from Kent, is damaging his business, and he wants it removed.
Mr Read says the mobile phone he bought from Mr Jones was damaged, and he will not retract his "honest opinion".
eBay says honest feedback is the "lynchpin" of its site - but it has promised a better dispute procedure.
Mr Read, of Herne Bay, says the £155 Samsung phone he bought from Mr Jones in an eBay sale was not the model he had ordered, and arrived in a damaged condition.
Even though Mr Jones refunded his money promptly, Mr Read still posted "negative" feedback on his eBay profile.
In doing so he says was only acting in line with eBay guidelines, which encourage all buyers to publically rate their sellers so that "informed decisions" can be made.
He wrote: "Item was scratched, chipped and not the model advertised."
He said: "I was just doing what I was supposed to do - give my honest opinion.
"The seller refunded my money and I had no problem with his service.
"But it's a fact the phone wasn't the one I paid for, and that's what I wrote."
A few days later Mr Read received a letter from lawyers acting for Mr Jones - who trades under the name Onsalexuk - threatening to take him to court unless he retracted the feedback.
The letter read: "The negative feedback you left on October 3 regarding Samsung F700 was unfair and is damaging to my business's reputation and ability to trade.
"We require a signed statement accepting that the feedback is unfair."
Mr Read said: "I won't back down - I told the truth, and this seller is just trying to intimidate me."
He said he had received "hundreds" of supportive emails from eBay customers worldwide backing his stand.
"Customers should have the right to leave negative feedback if what they have received isn't what they paid for. Otherwise people are buying blind."
But Mr Jones said he was determined to carry out his court action threat.
He disputed that the phone was the wrong model, and said phones sold on his site were advertised as "pre-owned".
He said: "I gave the customer back his money back and that should have been it. He had no right to post negative feedback which will show up on my profile and put off other customers."
Mr Jones said he wanted eBay to abolish its feedback system because he said the company was "siding with the buyer".
eBay spokeswoman Jenny Thomas said that a single negative comment was unlikely to affect Mr Jones's seller rating
She added: "Buyers are strongly encouraged to leave honest and fair feedback for a transaction, if they feel it is deserved and as long as it is not defamatory.
"We are very disappointed that this seller has chosen to sue rather than to attempt to resolve the buyer's problem amicably."
The row has exposed a growing gulf between buyers and the mainly small sellers on the eBay site - sparked by a decision by the company earlier this year to ban sellers' negative feedback on buyers appearing on the site.
Some eBay sellers say they are now at a disadvantage, compared with buyers who they say now use the feedback system to their own advantage.
There is no suggestion that Mr Read was involved in this practice.
On the social networking Facebook site, eBay Sellers Want Feedback Rights, sellers say some buyers are not paying for goods and threatening negative feedback unless prices are slashed.
One says: "Since this new policy came in, my incidence of non-paying bidders has increased... this has got to be due to the fact that buyers now think they can do what they want."
Ms Thomas said that eBay was aware of the "unfairness" felt by many of its sellers regarding its feedback policy.
In response, she said, the company was launching a new dispute system later this month, which would make it easier for buyers and sellers to resolve disputes.
A new "feedback revision" process will enable the seller to ask the buyer to change feedback, once a dispute has been resolved to the buyer's satisfaction.