I tried a free trial membership because I was sick of getting that popup asking me if I wanted to try it every other time I log in. I thought that it would go away if I tried the free trial.

Instead, it automatically charged my bank account $100 for something I never even wanted for free. I want my money back. How do I cancel and get a refund? This is ridiculous.

You can go to Help and Support, and search 

how to cancel premium membership?

I tried that already. There is no helpful information about getting a refund. I sent a message to the support staff as well.

If this is not resolved, please send me a private message.

The same happened to me!! 
 

If you need a refund, you'll need to open a ticket with support.

https://support.chess.com/article/346-contact-us

I put in a ticket with support 5 days ago and still haven't received a response. Is there a huge flood of emails?