The threat of legal action follows a string of complaints to trading standards officers and the emergence of evidence that the company may have gone back on assurances to the Office of Fair Trading.
The Independent has been contacted by angry Hoover customers whose cases suggest a systematic attempt by the company to discourage customers from taking up a free flight promotion launched in 1992.
Under the terms of the promotion, customers who spent more than pounds 100 on a Hoover appliance were entitled to apply for two free flights to the US or Continental Europe. Hoover was embarrassed by the success of the scheme and still faces a massive liability.
According to Harry Cichy, who set up the Hoover Holiday Pressure Group after the marketing scheme turned into a fiasco, a pounds 20m provision by Hoover's parent, the US company Maytag, is likely to prove inadequate. As a result, he said, the company is trying to discourage and stop potential flight recipients.
He said the number of pressure group members doubled last week to almost 1,300. About 2,500 names will make a High Court action viable.
The latest wave of outrage at the Hoover promotion follows the dispatch of 40,000 letters to customers telling them to accept proposed flights in writing 'before 5 January'. Hundreds received the letters, dated Christmas Eve, after the deadline had expired.
Letters to the Independent from Hoover customers confirm Mr Cichy's suspicion that Hoover is deliberately making flights unappealing or difficult to accept.
They show large numbers of applicants from the South of England being offered flights from Manchester, in contravention of a promise from Hoover to the OFT at a meeting on 10 December.
The dates offered by Hoover to many customers have also been criticised because they fall on consecutive days, increasing the chance that none will be suitable.
Hoover Action Group: (0442) 219725.