Capital one definitely puts certain accounts on "double secret" probation like you suggested. I had an Orchard card that went Platinum when they acquired Orchard and I was never able to get the limit above 1k, even after my reports were clean and I had used the card quite a bit. Card was 4+ years old by that point with 0 lates and decent usage for the limit. I was hesitant to combine that account because it was my oldest rebuild card at the time, but I finally did and now my QS card stands at 31k from combining and using the 2fer. I have to thank them for making me a nice prybar...but dealing with cap1 customer service is usually a painful experience.