Re: Credit Score
I think the old method of credit score (FICO) goes up to 850. Anything over 700 is considered excellent. I am assuming between 600-700 is decent/average. Below that you may have trouble getting a decent rate.
On the unauthorized charge, I am assuming your not paying it timely has already entered the credit report. I am assuming that, because if you contest a charge on a timely manner, it gets reversed from your bank statement pending resolution and thus never gets to the credit report. When you run your own detailed credit report, they generally indicate if you have paid balances timely. I think I read that any unfavorable entry stays for 3 years. I doubt if your bank will go back and rectify a negative entry in a prior period.
The new credit score goes up to 900, is not FICO and instead the three bureaues have joined together to rate consumers themselves on a uniform basis. So now you will have the same score from each of the three bureaues (or so one hopes), although the information that goes into generating the score will be different from bureau to bureau. The new credit score also has an A-F grade (A being the best, and F being you-know-what).
Hope it helps.