A family-of-five were left without heating or hot water for 10 days as temperatures plummeted below freezing.
Luke Smythe said his children woke up shivering after their boiler broke over the Christmas period.
Mr Smythe, his partner Jessica and their children; Willow, aged 11 months, Winter, four, and River, six, who is asthmatic, then waited days for the boiler to be repaired.
Baby Willow even started screaming because of the cold.
The boiler was not fixed until January 5 even though Mr Smythe, from Scarborough, contacted Insight Lettings on Boxing Day to tell them it had broken.
Gail Carmichael, the manager of the company, apologised for the “poor service”, saying it is “totally and utterly unacceptable”.
On Monday, Mr Smythe said: “I am trying my best to spread the word so that no other children have to wake up shivering cold and miserable because of this company.”
The boiler was finally fixed by Insight Lettings on Tuesday after various reasons were given to the family for the delay.
Mr Smythe contacted Insight Lettings on December 26 to inform them that the boiler was broken and an engineer from a maintenance company came out the next day.
Mr Smythe said: “After he left he said he would report the problem and we will get you up and running. That didn’t happen.”
Mr Smythe said that they waited at home for a number of days and after multiple calls they were eventually told by Insight Lettings that the spare part had been lost.
He claims this was not true as he found out that an engineer for the contractor had purchased the part but had not been told what it would be used for so had “carried it around in his van”.
Mr Smythe said: “We didn’t get any of that information from Insight though. It’s had to come from engineers.
“Instead of saying ‘Someone picked up the part and we had an error’ they just said they lost the part, which is ridiculous as it makes no difference to us.
“They’ve lied to us every step of the way. They’ve screwed up royally.”
Mr Smythe said that he was conscious that some of the staff were away for the Christmas period and offered to help in any way he could, such as by picking up the part that was needed.
He said: “I found the part online in 10 minutes. If I could do it why can’t they?”
Speaking on Monday, Mr Smythe added: “They just want to waste my time and give false hope. My kids are still shivering.
“Imagine being a 10-month-old. It’s not like you can pipe up and say ‘I’m cold’. The only way to react is to scream your head off. That’s what we’ve been dealing with.”
He also said that by law he and his family should have been provided alternative accommodation within 48 hours of the problem being reported but “nothing has been offered for nine days”.
He said: “I can’t explain how painful it is to watch your children be cold over something as stupid as people not doing their job properly.”
Mr Smythe contacted the Environmental Health agency and his local MP in a bid to put pressure on Insight Lettings.
After YorkshireLive contacted the company for a response on Monday night, Mr Smythe was then contacted by the CEO of Insight Lettings on Tuesday morning and the boiler was fixed in the next few hours.
Gail Carmichael, manager, gave a response to what had happened, saying that their partner company had sent round an engineer the day after the problem was first reported on Boxing Day.
She said: “Unfortunately a part was needed to fix the problem and that’s when an unacceptable delay happened and we and the tenant were let down.
“Although we tried to support Jessica and Luke between Christmas and New Year, we relied too much on our emergency partner to rectify the situation for us, which left Jessica and Luke without heating and hot water for too long, which is unacceptable.”
She said that management were informed of the issue on Monday and tried to find the family alternative accommodation.
Ms Carmichael said: “We have also offered them a gesture of goodwill to reflect the poor service that they’ve received.
“Although we have spoken to Jessica and Luke in person and will continue to do so, we have also acknowledged their complaint on social media.
“Leaving any tenant without heating and hot water for an extended period is just not acceptable to us and we let Jessica and Luke down. The key for us now is getting things resolved for Jessica and Luke and looking at what went wrong in the process so that we can put it right in the future.”
In their social media post to the Smythe family, Insight Lettings said: “This is totally and utterly unacceptable. You have had a horrendous nine days and it is not acceptable at all.
“I am really sorry for the experience you have had. It is not good enough.”
Mr Smythe said: “I just don’t want this to be forgotten about. I don’t want anyone else with kids and a wife to go to them and be lied to and told they will fix things when they won’t.
“People are trying to rent properties through these guys and ultimately they could end up like us and that’s not fair.”
The family have been given a month’s free rent due to the incident.