Brian Gaff formulated the question :
I don't think its got much to do with the make, my old machine was a Service
this one is a Panasonic and the same issues prevail, thankfully getting the
drawer out is easier on the Panasonic and running brushes and chemicals to
clean it all seems easier generally if a little messy!
I would also like to know why all machines only use cold water these days.

That is because they use so little water these days, that hot fill has
been found to be unnecessary. They usually waste a lot of hot water,
until the hot water gets to them, both in the pipe and time for a combi
to get hot, it is just a wasteful process with little advantage.

I sometimes boil a kettle and pour it in the dispenser, but it gunges
up much less with liquid detergents.