I purchased an app accidentally. I want a refund.

iTunes Store - Contact Us - Official Apple Support

Terms of the store are all sales are final but you can ask.

Please try: https://reportaproblem.apple.com

Also if it's necessary:

View, change, or cancel your subscriptions

https://support.apple.com/en-us/HT202039

Looking at my bank statement today, I see a charge for 59.69. I need a refund and close that app.

My checking account is overdrawn

Then you need to contact iTunes support and ask them for help. Nobody here can do it for you.