I asked what the benefits were and he said it would give independence between the hot water and the radiators. [ /quote]
Which it has
his quote was more than an alternative
Because he had additional materials and labour involved. Anyone who was offering a straight swap onto your existing system was willing to do so against current legislation and as such the quality of their work must be questionable.
I've not got what I've paid for
Yes you have. Total independant thermostatic control of water and central heating.
I do NOT have the rads working independently from the hot water
Because the bathroom radiator was already piped off the hot water circuit. Totally unforseeable considering the way in which your existing system worked.
What I am surprised about is that he has made no effort to put things right
Did you ask him at the time to do so?
but surely you'd expect him to offer to sort matters out for me for God sake even if it does involve additional payment??
Yes i would but have you asked him?
Ring him up and ask him to come over to collect his payment. While he is there tell him you are not happy with the way the bathroom radiator works on the hot water side and ask how much to swap it over.