I have been using a medium orange Meluna cup with a ring since November 2009, just for the nights during my period. A couple of days ago however, the ring snapped off when I took the cup out. I emailed Meluna's customer service about it, noticing that the cups that are on sale now have a much thicker ring (and also ribbed edges around the base of the cup, if I remember correctly). I got a reply within a few hours, and they are sending me a new one without any costs! Just wanted to let you all know in case the rings of some of your Melunas also broke off :)
(I'm not sure whether they would ask for postage fees or anything of that kind if you live in e.g. the US, I live in Holland and obv. that is not that far from Germany, considering shipping costs)