JP Chase C redit cards

I have had a visa credit card since 2006 and have never been late and always paid more than the payment . It now has a zero balance .Last week they sent a letter stating the interest rate would go up to 29.9% to all customers .This week I get a letter stating they have canceled my account.I just don’t see how they can just cancel an account .They it is because of higher balances of some other cards I have .This card has a limit of 8500.00 but I didn’t use it because of the interest anyway but i don’t think it is right for them just to cancel an account that was in good standing .This will hurt my credit in the future because of this. Is there anything i can do to protect myself from this hurting my credit .But they shouldn’t be able to raise the % rate like to anyone .My other cards the highest rate i have on any other card it 8.99%. I guess what is so crazy about this is they bought out the Circuit city and best buy accounts and gave me a credit increse 3 weeks ago .I would like you to follow up on this if you can please. Thanks