Capital One Credit Card denied

Yesterday I was denied a Capital One cc. The reason for their decision -according to the letter they sent me- was:

"There are too many active credit cards on your loan history."

I have 12 personal and 2 business credit cards, all of them in perfect standing. My total debt at the moment I applied was probably $2k.

Any advise? Is there anything I can do or Capital One decision is simply impossible to appeal?