The only thing you can do is contact the seller directly and ask them if they are prepared to cancel the order - if it's the car part from the UK, they should be agreeable to this as they accept returns and the DSR (distance selling regulations, applicable to EU countries) give the buyer a 'cooling off' period anyway, but in a lot of cases it is completely up to the seller. (PS if it is the UK item, the seller's listing notes that they are away until the 23rd of May, so you will have to give them a few days to reply).
