According to the American Bankers Association, 21 states and the District of Columbia have interest-rate caps for credit cards. The other 29 states do not.
Here are the states with their caps:
District of Columbia
14.45% to 18%
No limit for qualified in-state issuers. Limit for all other issuers is 18%.
18% for cards with annual fees; 21% for cards without annual fees
14% to 22%
Source: American Bankers Association
Typically payday loan and pawn shops escape any ususry limitations by not charging any interest. All the monies they recieve are considered fees and as such are exempt from any interest cap. There have been suits in some states to correct this, with some success, but not all states have acted as such.
So, to determine if there is a limit on the CC acount, we need to know under what states laws does the contract state are applicable. Often the state of incorporation is the determining factor but not always. Some states offer reater protections to the citizens of their state regardless where the creditor is incorporated.
If Arizona lawa pply, it seems there is no limit to the amount of interest they can charge. As I stated previously, many applications (and presumably subsequent contracts) state that the creditor can alter the interest rate for any reason at any time so there would essentially be nothing illegal about what has happened if this were the case.
I would still contact your states AG to at least find out their view of the subject. This also lets the state know what is happening with the consumers and hopefully causes them to enact corrective statutes (via the legislature of course)