If you don't like any part of your current kitchen it's probably not worth trying to salvage or refurbish any of it?
You have to think about how a kitchen is built up because a s/h kitchen will have to be taken back to its components to be refitted. Some adaptations are possible.
Units- these are basically just chipboard boxes, in standard sizes, although they can usually cut down eg base to wall or corner to straight. Interior fittings can be changed.
Doors/fronts, these are often interchangeable so the same size door might be on a wall, base and corner unit. The opening direction can be changed or moved.
Trims- end panels, wall unit cornice/pelmets strips, plinth (kickboard). These are usually cut to size to fit the installation so you might need extra ones.
Worktops - also made to measure but if long enough and with the right layout you might re use some.
Appliances usually are standard size but there still might be some fudging to get the neatly fitted. Sometimes it a freestanding appliance is easier to deal with and doesn't need a unit.
Ex display kitchens are often very small or if large, expensive.
Ones taken out of houses can be a bargain. Either way you have to list out all the components and work out if you can build them back into a kitchen design that suits you and what extra parts you need to buy. And ideally draw it out to the millimetre for the fitter to work from. (As opposed to DIY where you might work it out as you go along).
I have done this but I am a designer and I love details and measurements! It's very satisfying and a way to re use things.
Having said that, your existing kitchen sounds rubbish if falling apart this soon . Do you know where it was from? What exactly is "warping", do you just need to adjust your hinges?