In the UK this is protected by consumer law under the terms of the The Consumer Rights Act 2015. Anyone who bought their devices direct from British Gas should write to them saying that they want repair, replacement with equivalent devices that will work, or a full refund.

There is no time limit, only "reasonable", which for something that is fixed into your house, 20 years seems reasonable to me. You could settle for prorating the 20 year life, so if you've had it 5 years then they will refund 75% or something.

British Gas is easily big enough to absorb the losses, and has a lot of bad press at the moment because of the profit it has been making. It would set a good example for future cases.

https://www.which.co.uk/consumer-rights/regulation/consumer-...