I had a trial and cancel within the 7 days and I was charged

1.

If you have received an invoice from Apple, on every invoice from the Apple Store and/or iTunes Store always states what you have purchased (and/or concerns a subscription) and the amount.

Tap on Report a problem on the invoice.

Or try to ->  Request a refund for apps or content that you bought from Apple.

Request a refund for apps or content you've bought from Apple – Apple Support (UK)

If you have requested a refund, you must wait until Apple has approved. Then you will receive a message from Apple.

Refunds are not guaranteed. For more information, see the Terms & Conditions.

2.

See also the following Apple articles:

View your purchase history for the App Store, iTunes Store, and other Apple media services

View your purchase history for the App Store, iTunes Store, and other Apple media services - Apple Support

How apps, content, and subscriptions from Apple are billed

How apps, content, and subscriptions from Apple are billed - Apple Support

If you see "apple.com/bill" on your billing statement

If you see "apple.com/bill" on your billing statement – Apple Support (UK)

3.

If the invoice has to do with an app that has a subscription associated with it, see -> Delete apps on your iPhone, iPad, and iPod touch -> Delete apps on your iPhone, iPad, and iPod touch - Apple Support

• If you delete an app, it doesn’t cancel in-app subscriptions that you might have. While deleting an app, you might see a Cancel Subscriptions option. Learn how to cancel your subscriptions.

If you don't want to continue a subscription you need always to cancel that subscription in time, see the following Apple articles:

If you want to cancel a subscription from Apple

If you want to cancel a subscription from Apple - Apple Support

If the subscription that you want to cancel is not listed

If the subscription that you want to cancel is not listed – Apple Support (UK)

First confirm you have canceled any subscription automatic renewal (if you simply delete an app this does not cancel subscriptions):

Review the information in this support article by clicking on the link to learn how to cancel a subscription from Apple. ➔ If you want to cancel a subscription from Apple - Apple Support

• "If you signed up for a free or discounted trial subscription and you don't want to renew it, cancel it at least 24 hours before the trial ends."

• An existing subscription will normally continue until the end of its term and may then renew automatically. Stopping automatic renewal is effectively canceling it. "If you don’t see Cancel Subscription, then the subscription is already canceled and won't renew." The "Expires" date means the current subscription will just run until then.

• Read the article to see what to do about subscriptions that do not appear in your list. If you still can't find a subscription, contact Apple Support using the link at the end of the support article.

• Canceling a subscription does not automatically start a refund.

Finally, follow the directions in this support article about how to request a refund for apps or content that you bought from Apple ➔ Request a refund for apps or content that you bought from Apple - Apple Support