The Independent Television Commission has launched an investigation after it received complaints from 70 viewers about Granada's decision to screen the 75-minute special on the honeymoon of characters Raquel and Curly on ITV after it had promoted it as exclusive to video for pounds 13.99. Granada has also received letters from several hundreds of viewers at its Manchester studios demanding an explanation.
Some 750,000 people bought Coronation Street - the Cruise on video, making Granada an estimated pounds 10m. But many say they only did so because they were led to believe it would never be shown on television.
In fact less than four months after it went on sale in December a shortened version was shown on ITV on 24 March.
More than 16 million viewers watched Raquel and Curly's antics as they joined a luxury cruise only to discover that they had no tickets and could not even share a bedroom.
Three other Coronation Street stars also featured in the special: Alex Gilroy, Mavis Wilton and Rita Sullivan.
Yesterday an ITC spokeswoman said that following Granada's announcement that it would be on the nation's television screens last month they had been inundated with complaints.
"We've had around 70 complaints from viewers who bought the video on the understanding that it was exclusive to video and then a version was shown on TV," she said. "We have asked Granada for an explanation and we are awaiting their response."
What viewers perceive as the cruise "con" has been worsened by ITV claims that Granada had known all along it would be shown on television but cold- bloodedly gave the opposite impression to maximise profits. One source said: "This is the consequence of their drive to push up profits. They are getting greedy."
A Granada spokesman admitted that it had always planned to put the honeymoon episode on television, and had deliberately removed the pre-printed sticker saying "Only on video" after the television showing.
But he denied that buyers of the extended episode had been misled. "It's grossly misleading to extrapolate from the 70 complaints the ITC claims to have received as being representative of the three quarters of a million people who bought and enjoyed the video," he warned.
"Initially it was made available exclusively on video and we had an agreement with ITV to make a version available to them once a suitable period had elapsed. The video enabled viewers to see the honeymoon immediately following the episode showing the wedding."
The row on the 35th anniversary of Britain's best-loved soap opera reflects Granada's increasingly commercial approach to ITV's "jewel in the crown".
Last month it announced a pounds 10m sponsorship deal with Cadbury's for the show and it also offers lucrative studio tours, books and a magazine linked to the programme and even the World of Coronation Street, in Blackpool.