Order cancelled and refund agreed, but refund not made and order delivered

CrustyGoth

I ordered an item from a French company just after Christmas as I was unable to find it for sale anwhere else. A few days into January I received an email to say the order had been returned to them and they apologised and issued a refund - no problem, I assumed it was some issue with Brexit and the lorry being turned back for some reason.
After the refund was completed I ordered the item from them again and the next day they confirmed it had been sent. There was a tracking link for the parcel provided and this showed that within a couple of days that the parcel was in the UK and with the courier for delivery. Two weeks passed and nothing was received and the parcel still showed as being with the courier for delivery so I contacted the company asking what was happening as the courier website was in French with the exception of the tracking page which offered a translation.
My email was completely ignored so a week later I emailed again to advise if they were unable to deliver my order or update me then I would like a refund. A week later and still being ignored I sent a further email to advise I would be raising a dispute with Paypal for a refund.
When looking to raise the dispute with Paypal a message advised I should contact the company first but gave a different email than the customer service email from their website and advised they would respond within 24 hours, so I sent a further email there advising that as over a month had passed I wanted to cancel the order and receive a refund.
The next day they emailed to confirm they were refunding me and I would receive the refund within 10 days and as the item was now available on Amazon I ordered it there and then and recieved it the next day.
Three days later the orignal order was delivered - I accepted delivery as I didn't realise what the parcel was until inspecting it as I was expecting other deliveries. I contacted the company again to advise them their parcel had arrived but as I had already purchased and received the item from elsewhere they should arrange for their property to be collected.
It appears from their website my refund has now been cancelled and they emailed to advise I should use the return sheet inside the box to return the item to them and also send evidence of the cost incurred to return it and they will refund me once it has been received.
As someone who is vulnerable and currently shielding due covid it will somewhat inconvenient for me to arrange to get the parcel to the post office to return it. Also I am unwilling to open the box as although I am aware it isn't an unsolicited package as such, I consider it to be their property as it was delivered after the order was cancelled and a refund had been agreed.
Obviously I can arrange to get my refund via either a Paypal dispute or a chargeback on the credit card I used on Paypal if needed, but where do I stand? Am I being unreasonable in asking them to arrange for their property to be collected? I was intending to email to advise why I was unable to return the parcel and that they would need to arrange for it to be collected and that if they did not make the refund to me as previously agreed I would need to go through Paypal dispute or chargeback.
We're only talking about £60 so it isn't really a massive issue, but any helpful advice would be gratefully accepted. Thanks.