Thanks for your response AnemicOak. I keep my kindle in airplane mode all the time, my concern is that despite the kindle being in that mode when attached to the computer when I de-attach it the wifi has turned on automatically.
With regard to the closure of accounts, I accept that this might be that I have become more aware of reports BUT the fact that Amazon consider this to be an acceptable response I find disturbing.
With regard to deregistering, I know how to do this but was wondering if doing this made the kindle an independent device (I accept that the wifi probably wouldn't work), having tried to find info on the net about using it as a deregistered device most hits seemed to be about how to deregister rather than using it after deregisteration.
Thanks for the suggested alternatives, have been looking at the pocketbook, will do homework on the others. I think I need to get something that will 'read' as many file formats as possible without tying me down to a particular provider.