The usual return rules (i.e. the SOGA) mean that you only have the right to return faulty / not-fit-for-purpose goods. A lot of shops offer returns because you've changed your mind, but that's not a legal requirement.
It sounds like you / she have just changed your minds, so that doesn't apply.
The CCR allows you to cancel your purchase within 14 days (IIRC, think that's calendar rather than working), assuming it's a distance purchase i.e. not in a shop.
If I was in your position, I would email them and tell them specifically that you're cancelling the purchase under CCR. If they refuse, then you can link them to information on CCR and tell them why that's unacceptable. If they still don't comply, take it up with your credit card company (as a section 75 claim) or your debit card company (as a chargeback request) and provide them with the emails as evidence.
If that time period has already passed, then you're stuffed.