Hi, bought last week hitachi

Hi, bought last week hitachi micro hifi AX-M136i took it back 'cause it kept 'freezing' in both eco and clock mode.
Got another, took it back 'cause it kept stopping mid cd and switching itself off. Got a third which we still have, but in eco mode it will not always allow us to switch on, so we then have to switch the power off at the plug and switch the unit on again to be able to use it, surely this can't be right? We love the system but three units in succession have failed in some way, please advise.