As others have mentioned this website is based in China where batteries cannot be returned from the UK by any courier company. The UK registered website has no UK based address to return orders. Be very careful if you order from this company as contacting this company is nigh on impossible. The online chat is always offline and the email server down/misconfigured so email isn't possible.
I bought a battery in error and had to ask PayPay to make contact with the seller using an email not displayed on the corporate website. Once contact was made with the seller I was repeatedly asked to return the battery to a Chinese address even after I informed them this wasn't possible from the UK. I'm now £50 down with no means of filing a RMA.