If they were sent out of the blue you have no obligation to return them. If they were sent by mistake as part of a remedy of for example a faulty TV, and you decide to use them, the sender is entitled to ask you to pay for them. The correct course of action is to inform the sender, who then has 14 days (according to what I read) to collect them at their own expense.
As long as you don't use them the sender has no right to redress, only to ask for them back.
As long as you don't use them the sender has no right to redress, only to ask for them back.