Everything Feels Like the end of the world

So, im a month away from my wedding and sent all the women included in the wedding (mil, mom, bridesmaids, etc) a planner of dates and times. Well to my surprise, THREE people want to back out of hair an makeup! Not a big deal i suppose, but i gave a list of people and services to my artist the end of january and finalized a timeline for everyone the end of february. The form clearly said CANNOT take away services but can add. Is this normal for hair/makeup artists to do and how do I handle everyone canceling and adding more stress for me to handle? Also, I want to add that my artist is TERRIBLE at following up with me. They forgot my engagement hair and makeup session but took me in anyways, then i paid and booked wedding with them anyways that day and she said she'd email a contract. Well, i never got it and had to email to let her know then finally got it that week. THEN i emailed 3 times to ask questions and schedule a preview and got NO answer! Then messaged on facebook and they made it seem like it was my fault. THEN i was messaging back and forth to set a date for preview and was told that day was good so i responded with a time...NO ANSWER! So agained i emailed and got a response a week later and they said sorry we dont have that date! WHAT?! So whatever, i made it for a different day. A week later i get and email asking if i can push it back an hour! Annoying but i agreed it was fine. I'm so frustrated and need advice! Do I just drop them or deal with it? What if they wont let the other people cancel? HELP