I'm really sorry for you Willow.
Apparently thefts from gardens are on the increase, in some parts of the country it's endemic, and many are sold at car boot sales, so beware.
There are some tips on here, plus some particularly spikey plants and shrubs, which might cut the theiving scum to ribbons, if they try again.
http://www.greenfingers.com/articled...n=HELPINGHANDS