Here is why it's irrelevant.
No, you are not obligated to accept a credit note instead of a refund if you have returned a faulty product or if you are entitled to a refund under consumer rights laws. If you're returning something because it's faulty or isn't as described, you are generally entitled to a full refund. A retailer's returns policy can only require a credit note for returns due to a change of mind or for items you are not eligible for a refund on.
The goods were not faulty and OP was not entitled to a refund so the credit note was correct. If you had just posted this then nobody would care.
Here's a more detailed explanation:
Faulty Goods:
If a product is faulty, you are entitled to a refund, repair, or replacement within a reasonable timeframe (typically 30 days for a full refund, then potentially repair or replacement for longer than 30 days).
Not faulty so irrelevant.
Change of Mind:
If you're returning an item simply because you've changed your mind, the retailer may offer a credit note or exchange instead of a cash refund, but you're not legally obligated to accept it.
It was a change of mind so she got a credit note.
Online Purchases:
If you've returned an online order within the 14-day cooling-off period, you are entitled to a full refund if you've changed your mind.
She didn't, it was about 6 weeks so irrelevant.
Credit Notes for Certain Items:
There are exceptions where a credit note may be the only option. This might include items like personalized items, perishable goods, or those with limited return policies (e.g., unwrapped CDs/DVDs).
Doesn't apply so irrelevant.