Update 26th November 2021:
I have now been speaking to the complaints team. After mistakenly asking me if I had a CO2 monitor or signs of CO2 illness (surely they meant CO), they have judged that they cannot investigate as too much time has passed.

I assume this means that if you find a fault, life threatening or not, SSE just have to wait a few months before they can wash their hands of it.

Obviously, this isn't good enough so I have asked for it to be escalated before we go to Ofgem.

24th November 2021
We had our boiler serviced by Homeserve (provided by SSE) in April 2014. The engineer failed to re-cap part of the boiler which was later discovered during an Emergency Gas visit to do with Cabon Monoxide.

For 7 months of our life including 5 months of pregnancy, we were subjected to continued Carbon Monoxide.

SSE claim they will speak to you about a complaint in a period of 24 hours. Having spoken to them again today, I'm now told 'we have too many complaints' and 'we'll be in contact before the end of the week'. I even have the recording of the staff member (he confirmed he accepted me recording) saying is disgraceful and he does not agree with his company stance.

You would think that a service that could potentially have killed a family of four would get a response. So far, nothing.

Cadent, who found the issue have raised this as a Riddor with HSE. Gas Safe are now investigating the engineer and what's the bet, SSE ignore me a little more.

Ask yourself - are you willing to risk the lives of the people you live with? I went through painful tests yesterday to find out how bad the Carbon Monoxide levels were. My 7 Year old and 8 week old are now being watched by us like hawks. My wife is upset and panicking as not only has 8 weeks of our new borns life been subjected to this but also 5 months in the womb.