get over my fear of phones

I cannot make any telephone calls as I HATE talking to someone I don’t know on the phone, I even hate calling distant relatives. I need to make several phone calls at the moment, one to find out about studying a course, and one to check my hotel bookings, and to extend it. I’m always terrified I don’t know what to say, and always worry the person on the other end is going to think I’m stupid. My mum usually makes the phonecalls for me (I’m 19!) but even she’s said she’s not doing it anymore, because I need to learn how to do it myself.