If you have ever had to be towed by a recovery vehicle or even by a friend, the towing eye cover can sometimes get damaged, or even worse, lost! I have had this happen to me when my clutch died a few months ago. I purchased a replacement (albeit second hand) through eBay. If you need another one, they are sold on Amazon.
When removing, and attaching the bumpers on your Astra H, there are some small clips that need to be removed or attached. These can quite often get distorted or damaged during the process. There are replacements from various sources and I have found that using the kit from Amazon great.