Getting charged $29.99 for simple premium that I never signed up for

I suspect you started a free trial while on their website, that turned into a subscription since it was not cancelled. Any trial/subscription that is made with a company directly is not managed by Apple, and you can only cancel those with the company. Many times, people are directed to these sites from a Social Media post or website advertisement. Does that sound like what happened to you?

For starting a free trial through an in-app purchase that is managed by Apple, you will see the trial period along with the cost and start date of the subscription if not cancelled at least 24 hours before the trial period ends. For those subscriptions that are managed by Apple, you can cancel them here:

View or cancel app subscriptions on iPhone - Apple Support

For a purchase managed by Apple, after cancelling the subscription using that link, you can request a refund. In most cases all transactions in the App Store are final, since you have already authorized them, but at times Apple may provide a compassionate refund, it should never be expected though. A refund can only be requested for a charge that has been processed and that is not true in your case as it would still show pending since the charge has not gone through.

Request a refund for apps or content that you bought from Apple - Apple Support