just go to a shop with juices and smoothies ( usually they make them  with yogurt ) and ask they to blend up something for you . They usually have silver beet and carrots for juicing . So you might ask for a blend of silver beet water melon and pineapple and you might need to put in a little water. I have asked for the same thing at boost . If boost is busy then  the young kids might not be able to cope but they have done it for me before. I have always found small health food shops to be very helpful . Hope this helps not sure about any shops that make just green smoothies but you never know. Simon.