I'm not quite understanding what you mean here. You are discussing two different subjects here, Family Sharing, and Apple Music Family Membership. Are you saying that you set up your Apple Music as a Family Membership, as opposed to a single membership? How much were you charged?
This excerpt is from the Apple Music page, http://www.apple.com/music
Experience Apple Music for three months, free. Whether you’re listening solo or looking for entertainment for the whole family, Apple Music has a membership that’s right for you. Individual memberships are $9.99 a month. Family memberships are $14.99 a month.2 And for students, membership is just $4.99 a month.
If you need to contact iTunes support about your Apple Music membership, you can use this link. https://www.apple.com/emea/support/itunes/contact.html