Ash, I think your letter to Chase Bank was exceptionally well done. It will probably make no difference to them. They are experts on a little phenomenon called "customer inertia". They calculated months ago how many (how few) customers would be sufficiently irate at the change in finance charge terms to cancel or discontinue using their Chase credit cards. That was part of the calculation of how much their profits would increase when they raised the rates.
We all love you, Ash, but to a banking giant like Chase or Bank of America, you are a nobody. You may want to consider seeking a smaller bank that actually wants to provide good service at a fair price to its customers. Shop around. Check out Bankrate.com. Simmons First National Bank offers a Visa Platinum card at a 7.25% APR and no annual fee; excellent credit required.
My best advice is to kick the credit card habit altogether. Pay cash, write checks, use a debit card...no hassles, no debt. Getting out of debt is a monumental challenge for many people, but it is worth the effort. Remember this little rule of thumb: For every purchase you make with a credit card, if you pay only the minimum payment each month, you roughly double the cost of everything you buy. That's right, that 9.99% or whatever your rate is computes to 100% in the long run if you carry over a balance on your credit card every month.
One more thing. The idea of costing Chase money for keeping your credit card account open with no activity may actually be to Chase's benefit. Be sure to read all the fine print to see if they have a right to assess an "inactivity fee".
Good luck!