Hi Jill718,
welcome to this Apple (user-to-user) Community!
Re: "I have been charged $59.99 for the purchase of this app that I never made".
Am no expert in this area, yet your post to the community deserves some response.
Fortunately Apple Support provides helpful guidance in various articles online (links below).
Wondering if you checked your Apple purchase history, and whether or not the app shows up there ?
Eg: If you use Family Sharing: could the app have been purchased by a family member
See: If you see 'apple.com/bill' on your billing statement - Apple Support
and
Get help with charges from apple.com/bill - Apple Support
___________________________________________________
Re: "I have requested a refund but have not heard anything".
You can: Check the status of a refund for apps or content that you bought from Apple - Apple Support
_____________
Also: If needed: The best source of help for a product not made by Apple (a third-party product) is the company or person who made it—its vendor or developer:
See how to: Contact a third-party vendor - Apple Support
or
How to contact an app developer - Apple Support
________________________________________________________
Re: " I’ve never heard of them and I certainly do not have this app. "
You may want to view this discussion thread providing tips about a "known scam" / fake Apple charges
what is this APPLE.COM/BILL 866-712-7753 … - Apple Community
Security: How to: Recognize and avoid social engineering schemes including phishing messages, phony support calls, and other scams - Apple Support
All the best :-)