You have no legal right in the UK to return items just because you don't want them anymore.
They arrived within the given leadtime, so you can't claim they were late.
There are different rules for refunds from Marketplace sellers, and different rules for purchases from overseas.
Whichever rules apply, I feel you will lose out under this clause from the Amazon help pages:
"We regret that we also cannot accept cancellations of contracts for the purchase of video, DVD, audio, video games, Sex and Sensuality products and software products where the item has been unsealed."