I havent had much luck with EUA either on CO. Granted, I'm only silver but of the last 15 segments on CO, only 2 were upgraded within the 1 day silver window. The other 5 I was eventually upgraded on I had to beg/ask the gate agent/pc/wc agent if my upgrade cleared. Overall I'm about 50% on CO which isnt bad for a silver, but I feel like I actually have to "work" to get the FC seat rather than have EUA do what it is supposed to do!