Why did Apple Music charge me for a free membership ?

I bought the monthly single membership, it said I get 3 months free membership, then they withdrew $21 the same day and another $1 after 4 days. The advertisement says 3 months free and I shouldnt be paying singular $1 fees which is very unusual for an app that says I can download 100000 songs using the membership, I know how to cancel the subscription but frankly I want my money back for the misleading advertisement.