YouTube Premium free trial was charged

I kept getting ads in the app telling me that I could get a free trial for a month for YouTube Premium. Today I decided to try it. I checked my purchase history and it said I was charged $17.34 for what I thought was a free trial. I already asked for a refund but I was refused to get one. I don’t think it’s fair for YouTube to charge me money when they themselves said I was getting a free trial.