I would have thought that if someone sends you the wrong item then it’s much the same as sending unsolicited goods and if they want them back they have to take responsibility.
You had a contract with the company to supply you with something and they have failed to honour the contract. Tell them that they have to organise the return or pay for the insurance for you to return them.
If they don’t want to play contact your card company and explain that the transaction needs to be cancelled because the seller has failed to fulfil the contract you had with them. Then contact the seller to say that the goods can be collected.