Father and son David Bellis and three-year-old Jacob were on a country walk when they came upon a grinning horse in a field and decided to take a selfie.
David later entered the picture into Thomson Holiday ‘Made Me Smile’ competition and were told they'd won a £2,000 trip – which would be their first family getaway.
But David was then branded "shameful and stupid" because he didn’t have the horse owner’s consent to use the photo.
The horse’s owner Nicola Mitchell told him he did not have her consent to photograph the horse – and she was contacting Thomson Holidays to complain.
David, who works on off-shore wind turbines, has since received messages from Nicola’s friends calling his actions "shameful" and demanding he hand over half the winnings.
David, from Prestatyn in north Wales, said his son Jacob had been crying and asking if they weren't allowed to go on holiday anymore.
Watch: Kevin Ashford reports from Prestatyn
Mum-of-three Nicola, also from Prestatyn, bought the horse Betty for her daughter Katelyne three years ago and Betty has since been taught to stick out her tongue. Nicola, a secretary, said:
David had been walking with Jacob down a path behind their house that goes past the field where Betty the horse was staying at the time.
David said the horse posed for the photos and clearly loved being in front of the camera and enjoyed the attention.
Thomson Holidays told ITV News that David and his family would still be going on holiday despite the row.