I have had the pleasure of experiencing the same type of treatment from Chase.
My wife and I also have a high fico score, been longtime Chase Mastercard holders--never late, etc. Our 4.5% fixed rate mortgage is also with Chase.
A few years ago...I got the Chase 3.9% transfer offer for the life of the loan/transfer. I had been paying it down, always paid more...didn't owe that much when I seen my next statement and this is what happened(late last year or early this year--can't remember).
The minumum payment went from 3% to 5%, plus an adminstration "fee" was added (I think it was $10)...this admin fee accrues interest at the normal rate (whatever that is) and every month the admin fee is added.
so 10 dollars every month + interest, etc, etc...
I called and this is what my options were---accept a higher interest rate (lose the 3.9%) and the $10 fee will stop and they will credit me the $10 they just charged me and my minimum payment will stay at 3% of the balance---or pay the balance in full and close the account.
Guess which one I chose?
I just recently read that the government got involved and made Chase reverse the admin fee charging and reimburse what they had taken.
They will never get my business again.
I started doing more business with my local Federal Credit Union. Should have done it in the first place.