You may be required to pay to return the goods, but you must have been informed of this as part of the pre-contractual information.
It would be impossible for you to do this without opening the packaging and trying the product out.
If you’ve ever ordered a product or commissioned a service over the internet, via email or by phone, then you are doing so under a Distance Selling contract.
The supplier must provide you with specific information related to your rights and their obligations under a distance selling contract.
This means without financial penalty of any kind – such as a cancellation charge or a ‘restocking’ fee.
The supplier must also refund any delivery charges paid by you, and any other costs related to the contract.
This information must be communicated clearly, but not necessarily in writing, before your order is confirmed so that you can be in possession of all the facts should you wish to change your mind.