Good article from which about boiler repair costs
https://www.which.co.uk/news/2018/02/how-much-will-it-cost-to-repair-your-boiler/
Also they rate build quality by brand but you have to pay to see that. I reckon Worcester Bosch are top of the table though. They are the Rolls-Royce of boilers and rarely breakdown. My parents (oaps) have one and it's going strong for two years now.
https://www.which.co.uk/news/2018/02/how-much-will-it-cost-to-repair-your-boiler/
Also they rate build quality by brand but you have to pay to see that. I reckon Worcester Bosch are top of the table though. They are the Rolls-Royce of boilers and rarely breakdown. My parents (oaps) have one and it's going strong for two years now.