Combi boiler - quality/reliable manufacturers

[PeteP]

Within a week of each other, myself and a friend have had major boiler problems that mean we are looking to replace our combi boilers. I'm lucky in that mine just needed a new pump and is now working again, but she has no heating or hot water - not even an electric shower.

Mine is an Ariston Microgenus and hers is an older Potterton (model unknown but higher end capacity).

Could somebody give us a little help as to who the quality manufacturers are these days and who is making the reliable boilers with readily available spares and good track record and efficiency?

I haven't started looking for an engineer yet, but she has already been quoted £3,700 by BG and £2,700 by a smaller local company. Does that sound about right? The boiler she was offered was available on the internet for just over £1,000, but she'd obviously rather the company supplied & fitted so that there is no confusion as to what he installs or who is responsible for what parts of the job and materials.

Any advice would be greatfully received.