First of all, Individuals who are under the age of 18 are known as ‘minors’ under the Family Reform Act 1969. A minor can enter into a contract at law, however, such a contract is ‘voidable’ by the minor before they reach 18 (and for a time thereafter).
Also under the law,
Online, mail and phone order sales
Online, mail and telephone order customers have the right to cancel their order for a limited time even if the goods aren’t faulty. Sales of this kind are known as ‘distance selling’.
You must offer a refund to customers if they’ve told you within 14 days of receiving their goods that they want to cancel. They have another 14 days to return the goods once they’ve told you.
You must refund the customer within 14 days of receiving the goods back. They don’t have to provide a reason.
If the company refuse to back off, or take money, etc, you can claim against them
Any money paid so far by your daughter, she should be able to reclaim. The company should refund. If they don’t, then contact your debit card provider. And seek a money back claim on the debit card.