Agree totally with knitting and other likeminded moderate posters.
The child is ten, cancelling Christmas and selling dolls is OTT and ridiculous.
Maybe OP you need to look at how your daughter uses the internet. A ten year old should not be using these sorts of games unsupervised and they should be password protected. Also talk to your bank about having your cards protected for internet use.
I also second people who say perhaps talk to your daughter about what happened rather than leaving her to be hysterical and fuming about selling toys and cancelling Christmas. Is she being bullied, does she have a gaming addiction, what exactly is the other children's involvement in this and why have they used her for game access and now decided to tell on her?
She is ten, use this experience in a positive way, maybe by teaching her something about the value of money and what £260 actually means in real terms and think with her about ways she can pay it back, i.e. chores around the house, going without treats and trips for a period, a lesser Birthday or Christmas present...
I would be letting her take ownership of this problem and some responsibility in solving it. The shock of your anger and upset should make her think twice about taking your credit card again.... unless you have an ongoing problem with her taking stuff that doesn't belong to her? Otherwise I think at ten she might not have realised the reality that using the details of your card equates to actual money [as in the stuff she sees in your purse that you use to pay for things] and may not have realised that £260 equates to two weeks worth of groceries or whatever... so this might be a useful lesson about the cost of things and money management, i.e. this is why Mummy doesn't spend £260 on games!