Where do I contact for my subscription issue?

I have annual subscription and at the same time, I have one payment charged for monthly subscription (renewed from past subscription)

I wrote Mosh around three weeks back using contact form within CodeWithMosh (Teachable account) but haven’t received response. I tried X and other means like replying to his X posts but haven’t received any response.

Where do I contact him for refund (monthly subscription?)

or simply, charge-back is the only solution?