Welsh tenor Rhydian Roberts was "robbed" of The X Factor title, according to fans of the ITV1 talent show.
The theatrical singer had been the bookies' favourite to win this year's series only for Scottish crooner Leon Jackson to take the title on Saturday night.
Leon's debut single - a cover of the 1998 Mariah Carey/Whitney Houston duet When You Believe - is released today, but fans have flooded the X Factor message board and Rhydian fansites claiming they were unable to vote for the Welshman during the live final.
One angry viewer wrote: "Rhydian was robbed in my view. For the last three minutes his line was blocked and that had not happened before, while another added: "The X Factor result was a complete travesty.
"As soon as Rhydian finished singing in the final showdown I tried to vote for him on at least 12 occasions within the allowed voting time (approx three minutes) only to hear a recorded message each time that the network was busy - try again later.
"How many thousands of other people had a similar experience I wonder? Leon fans had a much longer time span to vote for him. What a con!"
And 'sprinkle22' said: "I must have tried calling in about 50-100 times by hitting the redial button to vote for Rhydian - but I didn't get through once."
A poll on Xfactorblog has also revealed the huge support for Rhydian, with 83 per cent of respondents saying the Welshman should have won this year's series rather than Leon.
A spokesman for the show said that there had been no problems with the voting system but added that some viewers may have experienced problems with their specific phone providers.
Rhydian is contracted to Syco and is expected to release his own single in the New Year.