Ebay has the replacement cables.
They come with the grommet that takes the cable into the charger, so the idea is that you open the charger and solder in the new cable.
I've done that a few times and decided that it's not worth it.
I suggest that you cut both cables and join with a method you are happy with. The cable is coaxial, but only two cores so not too fiddly. You can use solder and heatshrink, connector blocks and insulating tape. I've put the ends into an automotive connector, so that I don't have to disturb the charger end if it happens again, but the choice is yours.