Bidslammer said I bid $550 for this item and won but my actual bid was only $500. The item sold for $545 to someone else.

Hello Liang,
Thank you for your question about the win status of the item ending in 4976. The correct status of the item is now updated. Let us know if you see this occur again.
Good luck on your future snipes. Please let us know if you have any other questions, or require other assistance. We are happy to help.