FYI, many of the portable EVSE units included with cars are labeled 120V but actually work perfectly fine at 240V. The manufacturer just slaps on a different label and plug depending on which world region it is sold. You can either make your own plug adapter to connect them to 240V outlets or buy something like the dual 120V adapters sold on this site:
www.EVDoctor.net
They also include a list of pre-tested 120/240V compatible EVSE units. You're still going to be limited to 12A but it will double the charging speed compared to using the same EVSE at 120V.