Residents of affordable housing developments in Edinburgh have said they are “living in a horror story” after being hit with a massive rise in their gas bill as costs are beginning to fall across the rest of the country.

The Harvester’s Way development has 180 properties which are all connected to a district heating system, where one huge gas boiler provides heating and hot water to all the homes.

It is billed as a greener and more efficient way to heat their homes but it also means residents are unable to shop around for the best prices.

Places For People Scotland, which operates about 1,000 homes across five sites in Edinburgh, has told residents the tariff for gas will jump 450% from 1 August, meaning people in a two-bedroom flat could be paying as much as £400 a month.

It said the new heat tariff was procured at the end of last year and reflected the market conditions at the time.

The unit price for gas can vary significantly and energy companies also impose standing charges, but the average UK unit price is currently just above 7p per kWh.

The Harvester’s Way residents were paying 4p/kWh but that is increasing to 22.18p/kWh.

Jakub Parulski, who lives on the development with his wife Kasia and two young daughters, said his monthly gas bill will rise from £60 to £350.

He said: “These properties were aimed at affordable housing for low income families, this is not affordable by any means and we are very anxious about this.

“The problem is we can’t boycott paying because we have pre-payment, pay-as-you go meters so they have us locked.

“We have no choice. The only choice we have is if we go cold with our small kids in the property.”

The low carbon heating and hot water district heat network has a smart valve in each home linking payments to access to heating and hot water.

As long as their account is in credit, the valve will remain open and they have access to heating and hot water.

If an account runs out of credit, the valve closes until a top-up payment is made.

Mr Parulski said he would not be able to sell his house because no-one would buy a property with such a high gas tariff.

“We are absolutely devastated. We are going to be locked in properties we cannot afford,” he said.

“People will lose their homes. Some of us are looking at being homeless, some of us are nosediving into poverty.

“It is impossible now for us to sell our properties. We feel trapped and this is beginning to be a horror story and is no joke for a lot of us.

“It is really desperate.”

The price rise was first introduced in April but delayed after residents complained.

They told BBC Scotland the first they knew about their tariff changing was when credit in their pay-as-you-go meters suddenly dropped overnight.

When Henda Sankareh noticed she had no hot water to wash her four-month-old baby at her rented flat on the Harvester’s Way development she thought the boiler was broken.

So the mother-of-two called the managers running the development to report the fault.

But the 30-year-old said she got the “fright of her life” when they told her there was no problem with the heating and instead she had just run out of credit.

She checked her meter and was shocked to see her monthly instalment had disappeared in less than a week.

She said: “They just told me the price had gone up so I needed to put more money in the meter.

“That’s when I got into a panic. All the money had gone in just five days. I had had no notice or letter or email to warn me.”

After residents complained they had been given no warning Places for People Scotland launched an investigation.

The company agreed to pay the higher tariff bill until the end of July but then residents would be locked into the new rates until the end of March 2025.

In a letter to residents, it said: “The procurement process requires us to adhere to terms and conditions known as the deed of conditions, which states we must get at least five cost quotes for price comparison before agreeing on a provider.

“Due to difficulties in finding gas suppliers for district heating, many providers chose not to participate.”

Scott Walker, 50, a quality control technician living on the Harvester’s Way development, said: “I got a fright and felt very angry when I did the figures in my head and realised this was impossible to pay.

“We can’t afford to move.

He added: “When we bought this house we were told this heating system was really efficient.

“We need to try to reduce the tariff. Obviously it has to go up but not that kind of percentage. It’s extortionate. We would take a normal price that everyone else pays.

“I want to get an independent review done of the heating system and how they have come to these figures.”

Samantha Walker, 52, said: “We feel claustrophobic and anxious. It’s shocking.

“We are now carrying around a wee electric heater from room to room for Molly, our daughter who has special needs as she needs to be warm, and in this day and age you shouldn’t have to do this.

“When we bought this house we were told it was affordable housing and affordable heating and it is not.

“If we can’t get this sorted then we are going to take them to court. They can’t get away with what they are doing.”

Angela Stevenson, who lives in a two bedroom flat on another Places for People development at The Green in Longstone, said her bills would rise from £80 a month to £400.

“I’m beyond angry,” she said.

“We are going to fight this.”

A Places for People Scotland spokeswoman said it had frozen the tariff at the lower rate while it reviewed customer concerns.

“After a thorough and careful review, we can confirm that the new heat tariff procured at the end of last year was based on expert advice and reflects the market conditions at the time.”

She said the previous long-term fixed tariff had meant customers had paid less than other people in recent years.

“The new prices are more reflective of the current market following the end of the previous contract,” she said.

“We would never want to see anyone struggle to meet costs and will continue to offer tailored support.”