Cancel my Avast premium security

Dear Sir/Ms,

I accidently bought the Avast Premium a few days ago and cant cancel my subscription and the payment was already taken.
I don’t see my subscription in my account settings, only in the software on my computer.

Please help me cancel it and get refund.

Thank you in advance!

https://support.avast.com/article/24/ (Orders/Subscriptions/Refunds)