Search is your friend - as are 17mm wheel bolt covers
This comes (up) for often than a male porn star!
Agreed bolt covers are £10 off eBay and look considerably better than standard nuts plus help a little with security as even with the special tool to remove them they can be a pig to get off. I've put copper grease in mine now
Mine a very rusty too and the cars only 11 months old! Will get them changed under warranty but if they replace with the same parts the same will happen again no doubt. Dissapointing penny pinching on a car of this value.
17mm AF nut covers (standard on most vauxhalls) ebay sell them in chrome, black, grey and lots of other gay colours for anything from £3 to £20 depending on what you buy. Best ones come with a metal removal tool. The plastic ones are rubbish and break. Fit them with some grease.