getting charged for mobile

So several months ago I got a new modem and called xfinity to set it up. During the process they told me about the mobile service which sounded good. I went with it and was sent a new phone.  However I never recvied it. I called xfinity and they said it went to the wrong address. I decided I wwasnt going to do the mobile anymore since the phone didnt come to me. A few eeks later I get charged for the mobile service. I call and explain everything and they gave me my money back. This happens nearly 5 times. Sometimes they dont give me my money back. I keep getting more charges, its almost like Im getting charged for the several months I havent paid. Ive asked them every time to stop the service but they either wwont or can't. Im seriously cconsidering leaving or possibly a lawsuit.