Most of the breakdown companies do a standalone EU cover which can be purchased for short periods e.g. 7 or 14 days. It would be worth asking your current provider how much to upgrade your own cover, but be aware if it’s though your car insurer, or not, it may be cheaper to buy an additional cover rather than upgrade.
But beware… policy wording varies form company to company and is very specific.. lots of threads on forums about ‘nightmares’ and large expense bills as cover not doing what it purports to do. E.g.
http://www.rac.co.uk/forum/showthread.php?15574-European-Cover-Concern&p=90832#post90832
Also, just make sure you have the right cover on your car insurance too.