Apple one free trial not eligible

I’ve recently finished a free trial of Apple TV and have just been billed £8.99 for this month. I was going to sign up to a free trial for apple one giving me music and Apple TV for £18.95pm but it says my current plan isn’t eligible for the trial. What does this mean, will I be billed £18.95 right away or will I just get the free month of music as I’m already paying for Apple TV or will I be refunded the £8.99 ? Not sure what to do. Thanks