I had a chase card for quite some time at a decent interest rate. I had never actually paid any interest as I paid it in full every month. Since the limit was relatively low, I asked to double it for a trip I was making so I could just charge my 4-week vacation expenses rather than drag around a huge amount of travelers checks.
Upon returning from my trip last summer, the first bill I received had an increase in rate to 23.99 %

I called them immediately and asked why my rate had nearly doubled and I couldn't be given a straight answer. So I canceled the card despite the representative's plea to reconsider, they even offered to drop my interest rate to 19.99 % which I refused.
Sure, I never paid a dime in interest even once for the time I had the card, but thats not the point. They just couldn't give me a straight answer for the rate increase and who knows, I may have actually had to spread out payments at some point and I wasn't happy they were hoping to make a fast buck because I asked to double my line of credit. Jokes on them I guess, because I paid the balance in full and they never did get a cent out of me!
I happily bank at wells fargo, my plat visa has a nice fixed rate under 10% and I like to keep it that way.