It's very easy to cancel, but you must log in to the stardoll account, choose my account, and there, you choose "cancel recurring refill." Also, you must be careful which membership you choose. It will bill you in a lump sum for several months of stardoll membership if you choose anything more than the first option that specifies one month.
Why all the drama? If you put limits on your child's access to the game, learn right away how to cancel (which was as simple as going to the "help" function,) and actively control when her membership is renewed, there shouldn't be a problem. Keep in mind that this is a membership site and it will bill monthly at the very least, and if you purchase the 3 month membership, it will bill a larger sum every 3 months, and so on. Stardoll is not a scam site.
The info is right there just below the box where you choose the membership. It tells you what you are buying, how much it costs, and how often it bills. I have an account for myself, my daughter, and 2 nieces, and we play safely together and have a great time with it.
However, I have no doubt that they can be unhelpful when you need assistance. I've heard many stories about lost or hacked accounts where they dont do much to help at all.
Product or Service Mentioned: Stardoll Membership.