...and presumably the normal 1.5 volt types (as opposed to 1.2v rechargeables).
In which case, after 3 new remotes, your attention must be on the soundbase itself.
If you give up trying to contact Canton, maybe take it to a repairer - preferably one that will provide free estimates.
Or, nothing to lose by opening the thing up yourself and having a look - at and around the infrared receiver.
Check that the receiver itself is in a position to clearly receive the remote's signal - and that there's no dust between it and the front window.
Maybe there's some identification on it (or its PCB) to allow you to obtain and fit a replacement (using only the minimum of heat necessary from a soldering iron).