Apple Music

good afternoon, I received a letter in the mail on June 3, 2019 with an offer to connect Apple Music for 3 months at a price of $ 4.99 the letter states that the offer is valid for 10 days. On June 12, I connected the service, but today I received a notification that the service will be written today 4.99 for the next month. Why does the offer in your letter not work? All conditions have been.