Here is what they did wrong:
1. Sent the wrong items, even though I specifically asked, to make sure, that they would be the correct items, and they assured me that they would be.
2. Said that when I returned the items I would only be refunded for the items, not the delivery costs, so I had to inform them of the law, that if I returned the full order, they had to refund delivery costs.
3. Expected me to pay for the return, and I had to inform them that they were liable for the return costs.
4. Tried to fob me off with some nonsense about 'compensation' for return costs being up to 10 Euros, and I had to explain, again, that, by law, they need to pay all of the return costs as they sent the wrong item.
5. Forced me to research and organise return costs, and pay for them, before they refunded them.
6. Rather than just refund the original costs, which would have meant the money went back to the card attached to my Paypal account, you know, how refunds normally work, they added the refund to my Paypal account. By moving the refund and the refund for the postage into my Paypal account I incurred a fee from Paypal.
So, after dealing with this company company, I've had to send about 20 messages, been sent the wrong item, had to organise my own return, had to argue with them about costs and the law, and they have not offered any sort of sincere understanding or apology, and I have spent time and energy I don't have, and am now out of pocket!