I ordered new windows. The supplier was too busy to measure up and recommended a fitter he works closely with. I specified a single opener in one bedroom. It’s been fitted and I realise it doesn’t comply with fire regs. The supplier agrees it needs to be a double opener with a flying mullion and that he would have realised this if he’d measured up. However he did specify fire windows on the other bedrooms so I think he missed this one. He says his fitters would not have fit the window as they would have realised. The fitter says whatever the regs say, he only has to fit fire escape windows in one bedroom, not al of them. So the one thing I feared from using a different supplier and installer has happened with neither accepting the blame and wanting to pay to rectify the issue. Any thoughts on where I stand on this please?