Double Payment Issue on GoodNotes Subscription — No Customer Support Available

I was charged twice for my annual GoodNotes subscription, and I want to cancel it immediately. I’m a student, and this situation has caused me financial difficulty. I’ve tried to cancel the subscription, but it’s not working, and I can’t find anyone to contact for help.

I’m very disappointed with GoodNotes, as there seems to be no real support or customer service available. I expect the duplicate charge to be refunded and my subscription issue to be resolved as soon as possible.