I didn't use a credit card, used my debit card. 
Thank goodness it was only a smallish amount.
I eventually managed to get a U.K. address for returns, was given options such as voucher off next purchase (
erm, no!) return with label and cost of postage deducted from refund, or return at my expense.
Went for return at my own expense, as by the time I had squeezed the nasty horrid top into a small jiffy bag, it went as a large letter, so less than the £3 they would deduct if I had gone done the other route.