A young man with Down's Syndrome was refused entry into Birmingham's Legoland Discovery Centre because he had recently turned 18.
Ethan Wheale was turned away from the attraction this week despite having a Merlin Annual Pass.
He has Down's Syndrome and ADHD and has a mental age of about six years old, his dad Gordon said. The teenager plays with Lego every day and loves building walls.
He was taken to the centre by his aunt on Tuesday, August 9, but was not allowed in.
The rest of his family went on a day out to Harry Potter World but Gordon said it wasn't of interest to Ethan.
Legoland Discovery Centre has said the policy not to allow groups in without a child is "in place to create a safe and welcoming space for small children and their carers".
Gordon, from Whittington near Lichfield, said: "My wife organised for her to take my eldest son and daughter and their two cousins to Harry Potter World.
"My middle son who has Down's Syndrome wasn't interested so he was going to go to Legoland in Birmingham which he enjoys and has been to numerous times.
"He's got a Merlin Pass, we booked it online and a Lego workshop. When his aunt got there we were told as he'd turned 18 at the end of May and you had to have a child with you to get in.
"He's got Down's Syndrome and ADHD, he's got a mental age of about six, he's always watching Bob the Builder. He hasn't got a clue why he wasn't allowed in.
"They made the journey into Birmingham, it was upsetting for him. His auntie had come from Australia to visit, it's the first time the family has seen her in two-and-a-half years."
Ethan and his auntie instead went to the Sea Life Centre, but as it is something Ethan is not interested in, he only spent about 30 minutes inside before coming home, Gordon said.
The family contacted Legoland on Tuesday after Ethan came home and was told the matter would be "passed onto higher management", Gordon said. "I said this is ridiculous, what can you do," he added.
"He was really apologetic and said he could understand my frustration. It was a very disappointing and frustrating day.
"My son got home and sat in front of the telly playing Lego. It's what he does pretty much every day, he likes building walls and towers.
"I would expect them to be a bit more pragmatic about it as he has only just turned 18, they could have let him in once but said ok in future he's only allowed on the adult's evenings."
A Legoland Discovery Centre spokesman said: “Legoland Discovery Centres are small, indoor attractions specifically conceived and designed to provide safe and fun environments for children aged three to 10 years old.
"Many of the key features in the attraction, therefore, are not suitable or designed for the use of older children or grown adults of any ability, including the soft play area and some of the rides."
"In order to constantly maintain a welcoming environment in which to play, the centres do not permit entry to adults who are not accompanied by a young child or children.
"We appreciate, as in this case, that this does occasionally mean disappointment for some of our older teen fans and we are truly sorry for this.
"However, this policy has been in place for many years, and was developed in discussion with our visitors from our sites across the globe.
"It is in place to create a safe and welcoming space for small children and their carers, and is clearly signposted on our website.
"We recognise, however, that the appeal of Lego crosses all barriers and that fans come in all ages and abilities which is why we also hold regular adult-only evenings.
"Our team explained this to Ethan and his aunt at the time, apologised, and instead arranged entry and a free behind the scenes tour at our nearby SEA LIFE attraction for them. We also explained our policy in a phone conversation with Ethan’s mum."