Cancelled an xfinity mobile line within the cancellation period but still being charged despite not activating it - how do I contact someone?

I added Xfinity mobile to my account with the free 12 year promo applied. Initially, I added another line with mine but they decided to cancel. So I cancelled it a few days later and removed the number/service from my account. It was never activated.

I am being charged the full amount for both lines including the activation fees for both lines. I should only be paying the activation fee for my line as the other was cancelled/never activated and my line should be free for the next 12 months. What do I do?