Youtube Premium - Double Charge?

I've been using Youtube Premium on a family subscription, which is paid by someone else. Recently, I found out that while having my family subscription, I was also being charged for the individual membership. I've been billed monthly for about 5 months now, all while being on the family membership and the individual membership. I already opened a refund request with Apple, but the only item it allowed me to select was my Youtube Premium subscription between June to July, and not the times I was billed before it.

Why can't I request a refund for the subscription before June?