“Legalized Thievery!”

We just received a letter that our interest rate on our credit card will be jumping up 5.00% to 20+%! And that hike will also apply to our outstanding balance! We're outraged! How can they do this to their loyal customers? We have our mortgage through them and this one credit card. We're really upset and will have to opt out of the new policy and will pay off the balance as soon as possible, in order to avoid paying the extra money to them. What are we to do????