Bad purchase price

[Smartspaces]

Tonight at 6:12 Mountain Standard Time I put in a purchase order on Coinbase. I got filled at $6,884 per BTC. As I reviewed the order ex post facto I found that it had never traded above $6,800 before or after. What can account for this discrepancy? This clarifies one of BTC's largest problems, i.e. who can I call to verify / complain / argue about this situation? Am I stuck with this? Is there no appeal in this dark matter? Explanation?