I had a Vaillant Eco boiler fitted just over a year ago. I find it takes a lot longer to get the house up to temperature, so that I have to have it turn on about forty minutes earlier than the old one. The water takes longer to EP warm up too. It's like the eco setting on my car's auto gear box, which takes longer to get me up to whatever speed I want to cruise at.
It's about to be serviced, and when the engineer comes I'll see what he has to say about it. It may just need the settings changed. The instruction booklet for "the operator" are incomprehensible to me so there's no way I can check for myself.
From what you say you don't understand how you should use central heating. I'd say that goes for maybe 99.99% of the population too including my wife!
Two years ago we had a Vaillant system installed and its fantastic. Not only are we warm but the gas usage has gone down in this 5 bed detached house. My wife comments 'The room is warm but the radiators are cold' and that is exactly how it should be.
You have to understand what actually keeps you warm and its not hot stuffy air that is uncomfortable, over-heats you and then you freeze. I've spent many years like that because like you my wife has no idea how CH should be used and tends to use the thermostat as you would for say a fan heater.
The science. What actually keeps you warm is infra red radiation and not hot air! This means that you have to keep the walls warm enough to radiate in the infra red part of the spectrum and what is misleading is that a wall can be to the touch feel cool but will if hot enough keep you warm.
A good example of this is a South facing wall in Summer. When the Sun goes down and the evening cools and you walk past that wall you'll feel warmth on your face from infra red radiation from the bricks. However if you touch them they'll feel cool.
I have installed zone controls in every room so that each can be individually controlled. Its on 24*7 but the rads in each room only come on if necessary in order to maintain a minimum temperature to keep the walls warm. The boiler is also weather compensated which means that the circulating water isn't any hotter than is needed. As for hot water that is controlled by a tank thermostat so is always ready when required.
My wife now loves this system that she can control with her smart phone. If her office is too cold she can give it a temporary boost to a higher temperature for a set time. This means that we can keep the rooms warm but boost the temp when we want to laze in one of them.
Oh washing machines. I installed a top-of-the-range AEG around 17 years ago. My wife has subjected it to much abuse by running it overloaded and for many years all day every day. After a hard spin the machine walks out into the room! We have had one failure when the filter clogged (and I fixed!) and thats it. However I cringe at the abuse its taken so am wary that its time will soon come. Like most things its not make vs make but rather quality vs quality. I see it in everything. The top expensive models often made in the UK or EU are long lasting and often can be repaired 20 or so years later. However the cheap products from the same quality manufacturer are often outsourced to China and are by comparison just cheap crap that fails PDQ. This applies be it a toaster (I had mine refurbished after 30 years whilst the flashy cheap stuff fails and has to be binned) or a laptop thats virtually unrepairable at the cheaper end but the pro range goes on and on.
Cheers
DV