My husband is in prison I have a account with you he has set up without permission I don't know what to do

My husband is in prison for assault on me, I cannot retrieve voicemail from my phone number, my call backups says I have missed hundreds of calls but won't the numbers are not listed I have over 70 voicemail message s but when I try to retrieve them I only have 4 I also have a voicemail message I left from me on my current number calling from the phone I left the message for how can this be